I'm surprised no one has chosen Ali for the jab. Particularly when he was Cassius Clay and before his 3 year ban from the sport, the way he controlled Heavyweights with the jab, and with his footwork of course was unbelievable. You couldn't come at him because that he would just pepper you with that jab, and with the movement he could just dominate a fight with the jab. I mean look at the first Liston match. Sonny Liston could barely even get near him that jab and the movement, it was like Liston didn't know what to do and he ended up quitting on his stool out of frustration. Even in his latter years, he was able to stay effective despite slowing down by using the jab to control range. Larry Holmes definitely had one of the best jabs ever, it was piston-like. He studied Ali's jab and developed his technique for that by watching what Ali did to Liston and other great heavyweights.