Khan, Meldrick Taylor, Hector Camacho, Roy Jones, Ray Leonard was one of the fastest counter punchers of all time also. Gary Russell Jr.
Maybe not the fastest of all time, but the one at HW who I always noticed the speed of his hands more than anyone else was Eddie Chambers. I just always felt if I blinked I missed his punches.
Meldrick Taylor was very Quick.Maritzo Stecker Italian feather weight and Olympic champion was Also very Fast .Not much power from these two.
Cassius Clay when he wanted to be.....but many fighters are very fast...they just don't want to use it. When Joe Frazier first came up...he trained on the "peanut" speed bag.
Zab was no slouch back in the day Khan has blistering speed early in a fight it does tail off as he tires. Calzaghe was fast for a sm