RJJ had an incredibly ability to go from being completely motionless to having already hit you before you could react. Most fighters tend to fight in a rhythm and they'll use this movement to disguise their punches and remain fluid....Jones could stand totally still and seem to tighten up and still land on you...he was just insanely explosive.
Yup, but he did it up at MW-LHW. He was believably fast for his size though. Still think Hector was faster.
In terms of pure handspeed, prime Camacho. That is, the fastest distinct, well-placed punches from different angles. Taylor's flurries were fast, but flurries are something a bit different. The combo at 0:33 here just makes me laugh. https://www.youtube.com/watch?v=0TFsEM4vXxY P4P, hard to argue against Roy.
Prime zab Judah was incredibly fast. The guy had the tools to be great. Mentally weak but incredibly fast n talented.