Khan also has a pretty good jab, but he doesn't use it much. Mayweather doesn't use his much either, but when he does his jab to the body is great.
I really like Kazuto Ioka's. He hasn't fought in forever so I don't know if rs inactive, but Troy Ross has a pretty killer jab. Dzin is past prime now but made a good living off his jab.
Cotto, Floyd (especially to the body), and Khan. Cotto stands out though, he used it very effectively against Floyd at times.