At Wade's peak he wasn't comfortably Top 3, because his peak coincided simultaneously with Dwight's and people do either misremember, or just disregard, how great Dwight was. He and Wade both peaked at the same time and while different positions and all that, my remembrance of that era is that it was Dwight and Wade right after Bron and Kobe, and Melo a half step behind...
So I also don't think that Wade peaked that much higher than Melo. And as bad as some of the circumstances of Wade's prime was, Melo wasn't afforded the best circumstances, either. And he was in the tougher conference...
Wade's peak he was a Top 4 guy, Melo was around Top 5 at his peak. Both are #1's but Melo had the tougher conference and path and was never afforded a last really good version of Shaq-esque player to help aid him to a title...