My top 6-10 :
6. Atrocitus : One of the best trait (if not the best trait) in the game, good damage, good mixups
7. Supergirl : Large number of tools, good damage and very good trait
8. Captain Cold : Awesome trait, good zoning/anti-zoning tools, good set-up gameplan and good damage
9. Poison Ivy : Great spacing/anti-zoning/zoning tool, builds a shit ton of meter, restand for a bar, good mixups and good damage
10. Black Canary : Very good damage, good footsie tools (b2/f2) and awesome trait when fully charged (even if it takes a long time before getting to the level 3) but very unsafe