Wilt is really the guy you have to compare everyone else to. His big weakness is his lack of focus. I don't think there's been a more talented player, and when he had it all working, such as in '67, I don't think a better player has ever existed. But the guys above him were better at maintaining that focus year in and year out.
The greatest offensive player in history. People have often spoken of "the next Jordan", but "the next Magic" players are much more rare, and for good reason: The few players in history who have such top notch court vision tend to be able to excel in the league even if they're short and unathletic. That kind of brain, in a body like Magic's, amazing.
Dr. J is another that gets underrated, but for different reasons. People forget or dismiss what he did in the ABA. If you analyze what he did in the last season of the ABA while looking at how the teams involved did following the merger, it's quite clear that there was no player in the world playing better.