Added 3 minutes later
I would suggest making it so that for some factions, certain levels could be chosen. For example, after building one building, you either build a building for unicorns or for pegasuses, and the second one is blocked (like in Heroes 4). This would resolve this endless debate. Ents... Unicorns... Pegasuses... Who should you put in, and who should you remove?
Centaurs are needed, BUT LEAVE THE BLADEDANCERS!!!