I dont think the list is..well depends.
I mean defense worked only if you get hits. And whos getting hits? Except the taunting tank, usually the one with highest dmg or the squishiest one, like papa palp, raid han..etc.
So like Finn or Fives (and vandor chewie), they dont have active taunt skill, are very durable now that can survive 2-3 aoes, so ppl want to keep them CCed and kill others first...
So I say keep those 3 with some kind of mods that boost dmg, or tenacity (finn dispells so thats helping alot), not defense mods simply no one hits them first.