The easiest is probably a vanguard trooper specced as assault specialist. The skill rotation is very simple and strong and you get your healing companion pretty early. The story is good as well.
The smuggler story is the funniest in the game. A dps scoundrel has stealth and a simple rotation as well. You don't get your healer comp until. 4/5 of the way through.
If you play a scoundrel dps properly there is never a need for a healer just a tank, you burst in let the tank grab aggro then start finishing things off one by one, as well as occasionally throwing an offheal (underworld medicine, spec 2 points into it) to keep ur tank up and give you an extra stack of upper hand.