I don't think you can really say with any surety regarding who is the fastest puncher. A fast puncher is a fast puncher and you are clutching at straws unless you have a Grand Prix stopwatch and get your You Tube videos together. Otherwise, it really is all just guess work and opinions.

Jones Jr, Ali, Taylor, Whitaker spring to mind, but the fastest of all time? It's just guess work. I'm sure there are plenty who have had that speed in the last 100 years.