Not really sure strong Champions are an issue, unless you are going to serious early lvl units that can rival them. I also thought Champions were the thing the game hinges on. Was I mistaken? Shouldn't they feel a bit overpowered? As Blizzard says (paraphrasing) "we want the player to feel overpowered, 'broken' even, but keep the game itself to be balanced". I understand it's a very fine line, but a good game always creates that illusion.
This was one reason the original MoM(Master of Magic) was so popular. Once you had Champions you could dominate the game and they were 'broken' no doubt, but they couldn't be everywhere. So other units had to fill the planar towers, cities, and other choke points.
Three biggest gripes about the game so far:
1. Navy/Boats - why is this still not in the game? If strategy games from as far back as Empire, have naval units why can't we?
2. Races and Units - they still feel generic. It's a fantasy game, and I'm not trying to be flip, but use your imagination. Magic only races, Flying races, Snakemen, Beastmen, Races that start with ranged combat units, non-humanoid races, firebreathing dragon races. This makes your normal units exciting to play, and gives the player the incentive to go to battle with them.
3. Game presentation: love the new color palette, but the game still feels really messy and frankly doesn't feel 'epic' in scale. I don't the city sprawl works very will, and I never zoom into my cities. Smaller cities would make the map itself feel bigger in proportion. Also really thinking about it, in game I'm a magic user, shouldn't my Cities float, or be drilled into a mountain, or make a beautiful Spiral Ivory tower?