IMO there's plenty of fighters that could rival the likes of Tyson and Ali with single shots, it's their combinations that set them apart. Haye had pretty quick single shots but wasn't anything special in the combination department.
yes true about his combo's not being as fast. the hard part of this question is there are a lot of fringe heavyweights that didn't make it to the top that have fast hands. Like Bruce Seldon, he wasn't that great but boy were his hands fast. The same with a young Shannon Briggs, very fast.
Well if Seldon didn't have the habit of falling down from the wind of a punch he could have done more with his career. Michael Dokes is a cert on a top 10 list.
Off the top of my head here's ten in no particular order. Dempsey, Louis, Patterson, Ali, Holmes, R Jones, W Klitschko, D Haye, Seldon, C Sanders