Did Pac actually outjab Cotto or did he out-time Cotto with his two best power punches? When Cotto threw his jab, I remember Pacquiao countering it more with a straight left followed by a pivot to the right (Cotto's left) or Pac countering it with a quicker right hook. I don't know how often Pac snapped Cotto's head back with a jab or outdueled him in a jabbing contest.
When it comes to jab I like to see how fast , sharp, hard it is and if it doesn't get countered often .. but move importantly timing and if it offsets the opponets gameplan with that said Mayweather ... wlad ... ward/gamboa/dawson
A good jab for me consist of a speed, snap, doesn't get countered but most impotantly has good timing and offsets the opponents gameplan ... with that said 1. Mayweather 2. Wlad 3. Ward/bradley/dawson/gamboa