First I'll say that I have hardly read comics so my exposure comes from games, the cartoon from the 90's, and fansite/wiki browsing.
Gambit is my answer. Gambit is suave and dandy-like but has a heart and beat a kill-or-be-killed youth that, while it has an impact on him as a person, he seems to have beaten for the most part. I think his power is cool, it's not omega busted or a concept I find stupid like Franklin Richards or Scarlet Witch or the Hulk, and is a little more interesting than just having an elemental power (I like Iceman, but...) or super strength/speed.