I got all 14 ATs to 50.
If I was going to do it all over again...Keeping in mind the game will probably be Issue 23.
High Priority: Controller, Defender, Corruptor, Brute, Tank
Mid Priority: Warshade, Scrapper, Stalker, Soldier, Widow
Low Priority: Blaster, Mastermind, Dominator
Forget it: Peacebringer