Hello,
Till now the best farming place for exp is Kingdom of the Sands – Powerslave battle, if you want to get up your troopers just get Edi and one trooper and you will get 800+exp/battle
Healer for what I know is the allied soldier has recover = magic + max hp. I have the undead allied soldier heal all = magic
Fighter I have - Soulless demon
Mage I have - Child of the damned
Gunner I have - Allied Bomber boy
Assassin don’t have yet.
Please tell me your opinions about the best troopers in-game but not Edi please.