The nice thing about this question is I can say that I seen every one of theses guys fight in person, with that written from a EYEWITNESS account it goes like this.
Taylor.. unbelievably fast and accurate, no slapping or palming punches (Watched him train before the Chavez fight)
Robinson...Always ended a hook with a hook, blinding hand speed at middleweight and accurate no slapping or palming punches. (Very first fight my Dad took me to in 63', against Giardello, Ray lost)
Leonard.. Fast, but often hit lower knuckles or palms in fast flurries. This is why he's rated below Taylor and Sugar Ray. (Watched him train for the Lalonde fight)
Mayweather... Got to admit, I just don't like the guy so my opinion is indeed bias but let me state, Floyd does the same thing Leonard did in fast combinations, getting caught up in the moment he slaps sometimes especially while going to the body watch youtube, video doesn't lie. (Watched him train for the Hernandez fight)
Whitaker..not that fast at all compared to the above, he was more elusive than anything, hard as hell to hit (Watched him train for the Senegal fight)
1) Meldrick Taylor had the fastest hands in boxing history
2) Ray Leonard he had blinding fast hand speed nearly as fast as Taylor but didn't turn his fist fully over
3) Robinson was so fast I hate to have him at 3 because he was about as fast as Leonard when he was a welterweight maybe faster but there just isn't enough footage
4) Floyd Mayweather Jr. very fast but not as fast as Taylor or Leonard or Robinson
5) Pernell Whitaker I hate to have him last because he was so fast but in this group he is so close to ^ yet it is only splitting hairs in the difference of any of these speed demons
It's tough between Taylor and Leonard, but I will give the slight edge to Taylor as he had blinding speed. Leonard is a close second and Robinson is third. Next would be Floyd, who is fast, but doesn't have the sustained blinding speed of the aforementioned and that leaves Whitaker at last, though he was the most pure boxer out of all of them.
1. Ray Robinson
2. Meldrick Taylor
3. Ray Leonard
4. Floyd Mayweather
5. Parnell Whitaker
Haven't seen too many fights of ray Robinson, but I would say Leonard's fastest. Mayweather is the most accurate though
