I thought about a poll, but I'm sure I couldn't cover everyone that people would vote for, so just say your opinion.
Right now I'd have to say Franklin Richards, although Scarlet Witch seems to be pretty close. They almost have a similar power set.
There was a point in time when the obvious answer was The Phoenix Jean Gray.
I think there was a point when Nick Fury would have been an acceptable answer too. In a different way though, his power came through information. He's the only guy that we would have accepted as being able to blackmail Thanos to leave Earth alone.
Oh, and Bendis or Quesada is a cop out.