It's not because a trait is common that it should be ridiculously weak. The leveling in Blood Bowl (LRB4) is pretty good, as you have standard traits you can chose every level, and sometimes, you can chose stat increase, or traits that are normally not allowed to you.

If the standard common traits were not so ridiculously weak, random progression would not be such a problem. 

+1, except to mee I seem to use 2 common traits rather  commonly, and those are +2 strength (EVERY hero needs strength to carry theyre gear, and i always find heroes with a diminutive 4 strength or so having trouble carrying around a dagger and a hat). and the +2 initiative trait, because initiative spam seems so important, for mages because they need as many turns as possible to spam huge death spreading fireballs of magmaishdoom, archers and heavy plated knights because they have a high penalty to initiative for some reason, and a +2 to the 14 base after armors and ranged weapons becomes rather important.

Sincerely
~ Kongdej

What would the stat bonus for common traits have to be for you to choose one over a specialty trait like Healer, Spell Level Increase, Impulsive, etc.?

+5 strength? +10 strength?

Enmity is kind of ... well I don't like being spammed with it early on

+3 would be fine for me if it was a relevant attribute. As said before getting + strength on mages or +int on guardians is not so good.

Honestly, given a choice between a compelling ability (something like "Monster Hunter: +50% Damage inflicted against single model creatures" or a tasty new unique spell that I would actually ever cast), and a stat bump I'm looking at something along the lines of a +5/+3/+3 stat bump (Let's say Str/Dex/Con, for the sake of argument) to make it likely at all for me to choose.

Now, that is also assuming that I know WHAT those stats do and the degree to which they will improve my character. At this point that particular aspect of character levelling is a "Have you memorized the breakdowns of how stats improve performance from the website"?

I do think a large part of it is that the stats aspect of our champions is REALLY opaque in-game, but they do need about 700% more compelling level-up choices.

I've looked over the traits list in the .xml, and it is pretty extensive.  And there are some traits (besides spell lists) that have other traits as prerequisites, so there is a loose tree of sorts for a few of them.

I would recommend decoupling the stat boosts entirely from traits.  While it is fine to have a stat boost included in a trait, the trait really should have another purpose (increased damage or whatever).  As has been pointed out before, some of the current traits may have been put in as placeholders.  IMHO, you should get 'x' points per level to boost stats, in addition to trait selection. 2 points per level for stat increases, or perhaps more than 2 but you can't allocate more than 2 to any one stat each level, should be more than sufficient.

As for some comments I've read about some traits being more useful than others, this is something that can be balanced through trial and error, with the more useless traits being tweaked/enhanced until they are competive.

I think that 'Path of the Warrior/Mage/etc.' should be something you pick almost immediately, with said choice being directly coupled to the traits that subsequently appear.  This will encourage specialty characters as opposed to the hodgepodge that the random traits thing is causing now.  And Champions out in the wild should have a Path chosen already, so that their 'purpose' is better defined.

Some traits are really combat effects, and perhaps these should be tied to your weapon/equipment choice instead of a character trait.  For those familiar with Kenata's weapons mods for E:WOM, you will understand what I am getting at here.

Finally, I think that traits should have a cost to purchase, rather than just picking one each level.  Essentially, each level you get 'x' number of points to spend on traits.  This will help balance the lesser traits against the stronger ones, as you can assign a higher cost to the traits that are deemed more powerful.  Under this cost system, purchasing traits not directly tied to your path should cost more than the ones that fall under your Path (Warrior, Mage, etc.).  Unspent points may be accumulated, to save up for more expensive traits as necessary.

This also balances 10th level Champions better against each other.  So that you don't have one 10th level champion that only had 'common' traits choices versus another 10th level Champion that had all the best traits to choose from.

On a sort of related note, it might be cool if you could 'train' a 1st level Champion every now and then.  This way you could tailor said Champion's purpose from the beginning.  There should of course be a cap on these (1 trained Champion allowed per city or whatever).  This could be a mechanic that would better encourage the development of the 'stay at home' Champions.

Randomness can be seen as the lazy man's way out when designing things.  This is why some RPGs have more staying power than others, and why I better enjoy systems like Hero System for designing and leveling up characters - because balance is at the heart of character design, not how hot your dice rolls are.

See.... It's information like this that would be really helpful to have access to during play in a strategy game.

I'm more likely to pick a +2 Strength trait if I know that it can lead to a power attack trait in a level or two.