I cant remember losing a game using a custom Altarian Beastmaster.

Depends on what you're asking. If your question is which of the hero classes you should be choosing at level 2 for early/mid/late game strength, then my answer would be:

Early Game - Damage-line Warriors work well, as those +3 attack traits provide a very significant boost at this stage of the game, though I'd wait to see what high-end weapons I get before picking a weapon specialization. Tank-line Defenders work well, if you don't mind having your champion act mainly as a brick wall, but it requires some care with your supporting troops to hold the attention of the opposing army on your champion. Developing a Defender along the spell-resistance line has some nice active abilities, but the passive bonuses are not generally useful. Assassins are okay but they rely on getting critical hits whereas Warriors just have higher base damage, and dodge is a little unreliable for durability. Damage Mages are weak because you probably don't have the good spells yet or a good mana supply for casting them, but summoner Mages are at their most useful, if you can get enough mana income to maintain strategic summons and keep them alive through a few battles. Support Mages are kind of in the same boat as damage Mages, but if you have Haste or Slow and pick targets well, they can still be very useful, as long as you keep a close eye on your mana reserves. Governor Commanders are useful, and depending on how quickly you level them and what you pick for them could represent a fairly considerable portion of your research or gold income, while Field Commanders provide a mediocre passive boost to your army and have a decent active ability accessible early.

Mid Game - Direct combat champions (Warriors, Defenders, and Assassins) are beginning to be eclipsed by trained troops. If you're lucky and find a good weapon in loot and buy or find a full set of leather armor, then these will still work well, but to keep a front-line champion on the front line you're going to want weapons which would qualify for late game troops (pikes, great axes, longswords, longbows) or you need to find a late-game champion weapon (Curgen's Hammer, the lightning bow that gives +2 damage per level, a few others), and at least for Defenders you're going to want to at least consider getting heavier armor. If you can't find a good weapon for a Warrior or an Assassin, then it's time to start considering using them more as a mage or archer than a part of the front line (I would suggest that using them as a support mage is better than as an archer, as a four or five figure unit of archers with even the first bow is likely to be superior to any archer champion, as my luck in getting the quest that awards an Ignys Shortbow is poor, and bows and ranged staves are rather rare in loot). Governor Commanders who developed the income or research traits should begin to be eclipsed by towns, while if they developed the Administration line you should be moving to the point where you have enough cities that parking a champion for unrest reduction is becoming valuable. Field Commanders should be granting enough of an accuracy bonus for your troops to almost always hit, but if you've got a decent fortress up (and by now, you probably should), the accuracy bonus is kind of unnecessary. The initiative bonus and the active ability, however, are very useful, and you should start trying to reach the other active ability you have access to, as your army should be large enough for this to be a very strong ability. Summoner Mages should begin switching from running around with strategic summons in their army to running around with trained troops, supported by tactical summons, as strategic-level summons don't really seem to scale into the mid and late game very well and you should now have enough of a mana income that you can summon at least one or two creatures per battle. Damage Mages depend on what spells you have access to, but they are starting to become strong. Support Mages should now have the mana available for casting curses upon entire armies of enemies or blessings on your entire army in almost every battle, and possibly doing both. Note though that you probably still need to be careful with your mana supply as any type of mage at this stage.

Late Game - Unless you found good equipment, all of your Warriors, Assassins, and Defenders should be used like archers or mages. If you were unable to find good equipment, then trained troops probably outclass your champions by so much that they can probably knock them out in one or two hits. If you found the kinds of equipment that late-game troops use, then you might be able to keep the champions on the front line for a little while, but they won't be able to deal as much damage as a late game unit of front line troops, and they cannot take hits as well either. All kinds of mages are fairly good at this point, although if your enemy has archers and you can't kill them before they act, your mage will probably fall, so make sure your mage has high initiative (if possible, buy your mage all the initiative-granting equipment they can wear in the shop despite the cost). Summoner and support mages should start branching out into damage spells, and summoners should look into support spells, since only the late-game summons are really worthwhile in battle anymore and there are only so many friends to bless and enemies to curse, and you should have plenty of mana. Field Commanders with the active that makes the whole army go are great, and the Command ability is still useful, but aside from that they should be looking into support and damage spellcasting or perhaps archery (but again, bows and ranged staves seem to be hard to find in loot) since they cannot compete directly with the troops they lead.

If you were asking which sovereign profession was best in each phase of the game, then:

Beastlords are good early and mid game if you develop them as curse spellcasters - tame needs to overcome enemy spell resistance to work - but start to lose out late game, as there are not a lot of beasts that are really able to combat late-game troops on equal terms, and the ones which can tend to be difficult to find, few in number, and hard to tame.

Bandit Lords are mostly good at the early game, as even by the late part of the early game your trained troops should completely outclass any bandits you can find. The starting units are nice, but nothing extraordinary.

Warlords are more mid and late game, as they essentially allow you to maintain two armies for every one you'd normally have. The bonus is still very useful in the early game, though, as you can field your normal early armies with a much stronger economy than you'd otherwise have, or you can keep your normal economy and have about twice the army.

Generals give no direct bonuses, but the longer you can keep them and their army alive, the better they and their army become.

Summoners are all about the early game. Shadow Wargs are virtually useless mid- and late-game, and the +2 level bonus to summoned creatures isn't bad, but it isn't great either.

Noble is always useful, but more so when your empire is large, so they're more a mid or late game profession.

Adventurer is more of an early-game bonus, though it might also tank your economy if you use it to get lots of champions too quickly.

Warlocks are for the mid and late game, when you have potent damage spells and the mana supply to be constantly casting them.

Hunters are for the early game, because extra damage against beasts isn't very useful at any other time.

Diplomats, in my opinion, are never useful, but that's more a result of my dislike of the game's diplomacy mechanics. I would expect them to be more useful in the mid and late game than in the early game.

I can't recall what other options do, if I've missed any.

Also note that this is my opinion, based on how I play. What's fun for me might not be fun for you, so I suggest experimenting to see what you like.

I'd add that with the way summoning is now pretty much a separate research tree with any decent results far off on the event horizon, Summoner is worth very little. To me, it's only benefit is providing a shadow warg from game start: useful if you're running a mage leader for a Pariden-like race with no melee ability to speak of.

hmm i see beatlord seems to work for me but people say its over powered is that true?

I think there are lots of good hero types because there are so many possible combinations.  They did a great job on this aspect.  Here are some types that I have found the most fun or powerful:

a ) Summoner - unlike others in this thread, I have had great success with Summoner and choosing all the summons.  What's great about Summoning is that you can create a permanent summon by using the strategic spells (i.e. Air Elementals make great permanent summons) or create temporary tactical summons that come with an additional spell benefit (i.e. Crag Spawns create stinking mud all around them).

b ) Fire Mage - this is probably the worst kept secret in the game

c ) Defenders (esp Henchmen) - as Trainers giving the entire army experience

d ) Warriors with bows - I think they intended the Assassin class to be the great bow users, but Warriors do great amounts of damage with their bows.

e ) Healers - Healers are awesome ... almost too awesome.  Don't tell Derek cuz he'll probably nerf it if he finds out.

My experience:

Traits:
Fire Mages are great through the whole game, as long as you make sure to have plenty of mana. Just make sure your army is not all fire, as fire resistance is not uncommon in mid- and late-game.
Air Mages are weak in early-game, but can be great in mid- and late-game. The damage of their spells is actually very random(despite the ensuring tooltips), but they have several spells that will be useful most of the time, and their Thunderstrike is not to be underestimated.
Life Mages are weak in early-game, useful in mid-game and great in late-game. They really buff your armys durability. Give them a ranged weapon or damage spells early on, to get full use of them.
Water Mages are very situational and random, which is why I usually don't build them at all. It's hard to know what effect you'll get for their spells.
Earth Mages don't have much fighting power and rather situational combat spells, but they can be very useful in getting around the map and harassing opponent races.
Defenders are ok in early-game, weak in mid-game and potentially good in end-game... Their use is very situational, depending on the rest of your army. With enough ranged power you will never have any use at all for a defender. With several good melee DPS you will barely have any use for it. In any other cases, it can be good.
Commander is not what I would pick in early-game, as I consider combat skills more important in this stage. In mid- and late-game they are very handy, as they can either boost your army considerably or boost your research and economy as much as any city would, on it's own.

Weapons:
Axes are always great, because of their cleave. It can be hard to find axes that match the damage of mauls, but I prefer an axe to a maul with a bit higher damage.
Spears are good in early-game, but usually weak in mid-game and end-game. You'll often have use for their impale, and the impale can also be used to strike foes that are just out of reach. One of the biggest problems is to find spears with decent damage, compared to the other weapons.
Hammer\Mace are good throughout the whole game. Their advantage is damage, which is both because of their Crushing Blow and because it's one of the easiest weapons to find with good damage. Their disadvantage is reduced initiative.
Swords are good throughout the whole game. Like hammers and maces, their advantage is damage, because it's one of the easiest weapons to find with good damage. They also give additional initiative, giving them more base DPS than hammers and maces.
I usually don't have much use for the extra counterattack.
Daggers are a joke. I see no reason at all not to use some other weapon, because every dagger I find has way too low stats to compete against any other weapon I have. They're even rather rare, while at the same time being weak... what's the point??
Bows are ok in early-game, weak in mid-game and great in late-game. The problem in mid-game is that you usually don't have any good bows by this time, while melee units tend to have good damage and good gear to withstand your shots. In late-game you will have new bows and accessories, which greatly boosts your ranged power.
Crossbows are a joke. Their Power Shot has a 1 yard range - who puts a ranged unit right next to a melee foe?? It would also require you to run out and meet the foe before you can use this ability. Except their Power Shot, I haven't figured any advantage of these.
Ranged Staff: Ok throughout the whole game. Their disadvantage is of course the low damage. Their advantage is to have pure elemental damage, which is useful against several types of foes. I noticed that several foes are invulnerable or have resist versus fire, but I seldom find the same versus frost, so I prefer frost staves.

Beastlord doesn't give you much use before you have established some mana regen, as the spell costs 40 mana and can fail. Once you have enough mana, they will be great throughout mid-game, when there are still poweful beasts around. In end-game there are usually only dragons and elementals around, and your beasts will be replaced with better geared units\heroes.

have to agree with joeball. pretty good explanation.

some random comments:

don't underestimate life mages. i've played a ton of very hero centric games and life mages IMO are the single best champions in the game, especially in the early part (probably won't need that much healing later when your troops can kill stuff quickly enough to take almost no damage at all). don't underestimate the effect of not losing production time for replacing lost units. with a dedicated healer, you can keep them alive. combine with some heavy defense units or a defender champ for a superpowered early army that clears dangerous lairs or conquers whole nations 50-100 turns before you could safely tackle them normally. they use up some mana to do their job, but quite frankly, burning 9 mana for 24 healing is a lot cheaper than wasting ~4-8 seasons of production replacing the unit you would have lost without the healing. also, don't neglect their spellmastery (the "prodigy" line is recommended, since that also opens the way to savant which will make your AoE heal instant cast) with decent spell mastery, they can shrink even the most powerful creatures and make them harmless.

Earth mages: in my experience, there's no real reason to make a primary earth mage. the school is solid as a secondary school for a support spellcaster, or as an alternate route for melee heroes (sacrificing some of their class traits to gain diamond skin and giant form instead). the first 3 levels are really only there for the buffs; the tactical spells at level 4 & 5 are brutally expensive, so it's not a good idea to build a pure "earth mage". pick the first 2-3 levels up when you can afford them and delay  4 & 5 until you have enough mana to not care about the high cost of giantform and diamondskin.

fire mages are terrible in the early game. you won't have enough mana to warrant casting that lame 10 damage flame dart that will probably get resisted and only do 5 damage. they become viable in the mid game when you get them to a higher level and have a more stable mana supply (and/or some other champ who unlocked water 3 for mantle of oceans). towards the late game, they can become super powerful, killing whole armies single handedly.

Defenders: don't underestimate them. while they are in def stance, they can tank whole armies that would just eat any of your trained units alive. i've had mid level defenders (~level 8 or something) with mediocre gear tanking 3 freaking umberdroths at once. those defender guys are rock solid. not very interesting to play, since they don't really do much besides passing turns and occasionally move a tile, but very very efficient. 

as for champion weapons:

axes are pretty solid for warriors with axeman - 75% extra cleave damage on top of some 40 attack value can be pretty powerful; other than that - meh

swords are great for the init bonus and the counter attack. standard weapon for defenders (slap on an item with poison damage over time for some added benefit); warriors with swordsman specc can be rather hilarious, though. swordsman warrior with guardian blade is a fun spec (decent baseline damage from lethal traits, so the low base attack of the item isn't such a big deal - and huge bonus to counter attack damage with 3 counters per turn )

daggers are perfectly useless for melee (except for the early game when an assassin knife is probably better than a rusty axe or something). they make very good stat boosters for spellcasters, though. a dagger with high init and a bonus to crit chance and crit damage can make for some fun moments when that flamedart unexpectedly crits for 300 or whatever.

bows: the equation is simple - shocking longbow (+2 lightning damage per level) - awesome, every other bow - somewhere between "ok" and "useless"

crossbows: haven#t seen a magical crossbow yet. don't think they are very useful. the only saving grace is that they are one handed, so you can have a shield in the off hand, but that's no compelling reason to use a weapon with -8 init penalty on a champ.

ranged staves: useless for champions. if you have to kill a banshee, just bring 1-2 units of trained troops with staves, or a champ with a damage spell.

melee staves: useless as a weapon; the stat bonuses are the interesting part (bonus spelldamage or bonus spellmastery can be more useful than the init bonus and crit chance on a dagger)

Hunter should give food when you kill beasts for your nearest city or capital.  That might power it up.

Banditlord- might be nice if it improved loot rolls/gave better chance of loot

Adventurer- maybe it should allow a 10% chance of being able to pick 2 traits on all your champs when you level up?

I wonder if anyone has tried warrior+decimate+high init as an anti-army unit.   That's an experiment for my next game.  Unsure if decimate is automatic or a skill.

The difficulty you describe just doesn't match my experiences... I've been using melee champs in every game, and although I sometimes fail at keeping them alive through early--mid-game, I usually don't have much trouble.
I wonder if this could be due to monster difficulty settings, or some other settings. I usually play with lots of monsters, but not very hard monsters.
If you play with less and\or harder monsters, then this could explain our different experiences - it means I get both more loot and more experience, which makes it all easier.

It's probably because by the point I consider mid-game, my focus is shifting from fighting monsters to fighting AI factions, and so I'm concerned about champion performance against troops (granted, AI armies may not be the best designed in the world, but they probably have access to equipment at least as good as your own, and if they haven't fallen behind in research and aren't primarily fielding old units they generally can hit harder and are tougher than your average monster). Also, I tend to find that by mid-game weak to moderate strength monsters are all but wiped out, especially in areas close to a faction's territory, and the few remaining monsters tend to be of a strength that I don't yet want to mess with.

The only monsters I'd really be particularly concerned about using mid-level, mid-game front line direct combat champions against are things like drakes and dragons, or perhaps the tougher skath. If I don't have an army backing the champion up, or if the champion is for some reason weak (for example, if I stuck the first champion I received in a town to wait for an army and then decided that the army I built for that one should go to the higher level second champion, so I left the first champion in town for a long time), then large armies of weak monsters or mid-size armies of moderately strong monsters can also be concerning, especially for champions like Ascian, who rely almost exclusively on dodge for their defense.