I did enjoy the Gal Civ II: Twilight of the Arnor's much more unique tech trees for each specie, but personally even when I play a map with all AI at 'ridiculous' level, with dense monster spawns and a large map, it's still extremely easy, due to the following:
1) Overwhelmingly powerful champion weapons, as stated above. At late game, if I let it get there, enemies' armor's high enough to reduce my damage, but otherwise a good find allows a blitzing of nearby factions early on. This is what I always do: find good gear, then blitz, otherwise it's plan B, which is #2:
2) A squad with charge and initiative (plus horses if you can do it fast enough), wins all the time. Like the issue with AI struggling with us players with tons of moves for units on Gal Civ II, like my massive ships with tons of fast engines and firepower, the tactical battles end quickly with my guys with clubs just charging into enemy troops. I can't win against drake armies early on, ofc, but other factions just die to this. Champions with haste makes it more ludicrously easy.
3) Champion's attributes, outside the magical trees for more spells, feel useless. Use know how to buff your units, be it tactical or strategic, and you'd win with the charging troops in #2 and/or uber weapons of champions. Most cities are not defended on my games, and anything invading territory's smacked with 'tremor,' the flames, whither (where available), and/or blizzard. Which brings me to
4) A few elite charging troops with or without champions can win games. Just continue to conquer towns and pump out units. Never worry about gold because . . .:
5) Equipment sells for decent price. I bankroll my Mongolian conquest of much of the continent through acquisition and sales of gear and silly useless but valuable trinkets, like the one that summons a dog or sand golem.
So yeah, game's buggy but easy as hell atm. Enemies don't use strategic spells at this time, unfortunately. No nuking of me with pillars of flame, and such.
My champions' skills are largely worthless, esp. as OP says, with the randomized choices at level up. My mages would always take whatever increases dodge or int, or whatever helps the army, when nothing else ups my spell selection. My favorite Verga, despite being a warlord, was archmage in death magic, despite all my efforts at him being an epic warrior.
No other faction had any unique way of fighting or resisting. With the same tech tree, I suppose I can't blame them. They even use my designed units against me, in droves, but still I gain initiative, charge, and/or nuke them with spells or occasionally a drake.
I must add that much of the loot were also useless in game, and the rare OP loot always stood out, and a champion that happened to luck out with tons of warrior/defender/assassin skills did shine with that item than one without such skills.
I don't want such epic weaponry or gear disappearing, since we're working in a post-apocalyptic word, and some awesome stuff ought to be lying around in the world. But the overall game feels like zerging works best. No matter what the enemy champ or mine has (and I've faced quite formidable enemy champions), pumping out good charging units with maces won most of the game. That's right. Maces ftw. lol