I don't mind Quinn being an a-hole. If he were useful to me, he would be in my party. But most of the time I see on the combat screen, "he is heating up!" and then the next round I see he is already at 0 HP.
He needs to either do more healing or given some better equipment/sets. There are just better companions out there to round out the party in most situations.
Berwyn is the proverbial jack of trades, master of none. He does decent damage, but ain't really a tank. He has a summons which can be useful as another target, but it's not typically as good as my own. He can heal some, but as good as Cait. Also his material hasn't been updated a lot recently. Guess we'll see what direction he takes when B starts submitting stuff for him.