Speed for me encompases more than how many punches you can throw a second. There are lame karate guys who can touch their knuckles off a heavy bag 10 times in a second with "punches" that wouldn't crack an egg.

When you factor in everything: 1 punch speed, combination speed, fluidity, ect, I'd have to say p4p Roy Jones was the fastest fighter ever.

Floyd, Ray Leonard, Gamboa, Meldrick Taylor spring to mind too, but who knows what order.