without mentioning cheapass infiltrators, my best and favorites are the slayer and basic old human adept
I almost never play as the slayer off-host, because EVERYTHING he does (except biotic slash) has double-sided delay and I just can't deal with it
but, when I can host, I sweep up real nice and almost never go down, can use him for detonating both techs and biotics quickly and at a safe distance, and phase disruptor has crazy dps, he's good for any situation really
when low and in the open, I can just charge -> melee combo -> charge and repeat until I can find a safe spot to teleport into, thanks to that DR boost during light melee
as for the human adept, pretty simple of course, 6/6/6/0/6 and michael bay it up, and with other adepts it's just a faceroll