@Steele

I hate to correct Ivan but max affection only gives you a 20% additional bonus over where you would be. Evolution then doubles that.
Still, at low levels affection bonuses are quite large compared to base stats, so it's less surprising that a low level max affection 2* out stats a 50% affection 5* at a similar level. As the levels go up, the affection bonus stays the same so the 5* will pull ahead in time.
Total power also doesn't even begin to include skills and abilities.
Because this game doesn't involve any actual player input in battles other than the occasional solar blast, glass cannons per se are less useful - your girls will take damage, since there is no control on your end on dodging/positioning or anything else. They have to be able to survive enough hits to take full advantage of their attack power until your units are so high level that they can usually one round enemies.