Here are some scenarios I would be interested in testing. I suspect that AOE damage magic (with initiative bonus especially) is too strong compared to everything, and that lack of complexity in the combat engine favors generic powerful stacks over combined arms or maneuver. But, that could just be wrong impressions based on limited information. Too bad Beta doesn't have some kind of tactical arena for testing.
If there's some tactical tricks that can help the "underdog" get a reasonable win percentage in any of these scenarios then I think this thread will end up being very interesting. If as I'm afraid, the team with more AOE power and max'd out generic units wins practically every time barring unlucky random rolls, then there aren't really going to be any advanced tactics to discover; in that case AI just needs to learn rudimentary building blocks like, cast powerful spells rather than weak spells in tough battles; maneuver for first strike / kiting if you have more moves than the other guy; focus fire; don't cast the same buff/debuff spell again if it's still active.
[edit: I should specify, when I say focus fire, that only applies to champions once you start target them. When fighting regulars it doesn't seem matter since they lose attacks as they lose HP, and there is no mechanism to encourage application of overwhelming force at a point such as limited # of counterstrikes, flanking, suppression, morale ... ]
Anyway, following with interest, hope that i am proved wrong 
A vs B
Team A: 4 strong melee squads, 2 strong ranged, 2 heroes with only +initiative and Fireball (or Blizzard).
Team B: 4 strong melee squads, 2 strong ranged, 2 heroes with all spells and any abilities EXCEPT AOE damage spells.
(IMO as a general design principle whatever is the strongest form of attack -- and right now I'm confident it's high-initiative AOE magic -- should have a defensive counter strong enough to bring other tactics into play somewhat regularly. correct me if I'm wrong but currently the only limiting factor is on the strategy layer, that the AOE attacker needs sufficient mana reserves to do it? and that's not something that the defender has any direct control over)
C vs D
Team C: 6 strong melee squads, 2 melee heroes with non direct damage spells
Team D: X strong melee squads, (6-X) strong ranged squads, 1 melee & 1 ranged hero with non direct damage spells
It would be cool if there was a different optimum number of ranged on different maps, or at different technology levels. Or better yet if there was another variable that came into the equation like horse to run down the archers. It seems to me now that a combination of design decisions in favor of speed/simplicity, pretty well discussed to death in all those "tactical combat" threads, that make maneuver tactics generally have only a weak impact on battle outcome.
corollary 1: mobility (for the very specific purpose of getting first strike or to kite with archers) is key. is it true that you always want every guy on a horse if possible? tactical combat would always be more interesting if there were advantages but also exploitable weakness to deploy a heterogeneous army.
[edit: corollary 2: can you design a tactical scenario where for equal cost you'd be better off with a mixture of two different kinds of melee infantry? ]
E vs F
Team E: Army of generic max'd out user-designed troops (use all three attribute slots, relevant trinkets, best weapon)
Team F: Army of *equal cost* made of any faction's elite "flavor" units (one or two attributes, no trinkets)
I'm just curious about this one. I'm a little sad that after a couple play throughs I never see the special units any more from myself or AI, but only my generic designed guys.