Im not a huge fan, but obviously Jones gets the No1 spot. Who's number 2, just put the name down IMO - Ali.
Roy's speed is not even human. Bill Caplan timed Ali's jab by using video framerate. Ali's jab lasted for 7 frames, while SRR's was 8. Ali SRR SRL Mosley in his prime was amazingly quick. Meldrick Taylor? Really though, after Roy (Though people will argue that anyway), it's pretty much all subjective without any way measuring.