These are not the best ever per say, but the up jabs i saw used so effectively in specifics fights. Ken Norton (performed best against Ali and it worked a treat for him in those fights. He would jab with Ali from below) Ray Leonard (Watch the Benitez fight the up jab won it for him. Ray was having trouble catching Benitez with a regular jab, it was driving him crazy, and then started using an up jab and had success finding him even put him down with an up jab IIRC) Pete Whitaker (Would make himself smaller then he was and then shoot an up jab. He did it in almost every fight and no one figured out how to avoid it)
Annoyingly, Holmes is an example of BOTH a great standard jab AND a great jab from the waist. He was the King of the Jabs at heavyweight.
Sergio Martinez has shown a good southpaw upjab. I think I read somewhere that Billy Graham was an expert at using a very well-timed jab from the waist.
Holmes had a great regular jab, but i actually don't think it was THAT creative. Lennox for example had a more creative jab IMHO.
Larry Donald used one. The thing is he should probably utilized a standard jab and he would have done better. I could really never figure out why he did that and he'd just use it as a solitary punch and not use it to set the table--something some of the other up jabbers have a tendency to do.
Bob Foster always springs to mind concerning this aspect, a couple of Lt Heavy Foster followers Jesse Burnett and Lonnie Bennett had good one's too.
Larry Holmes,,,,,,,Fast, Accurate and Powerful He could and did use it, to win many fights with 'one-hand only'. Sonny Liston,,,,,,Heavy-handed ham-fist A standard 'smash-face punch'. Cassius Clay,,,,,,,Lightning-bolt and Razor-sharp Could rip the skin off your eye-brows before you knew it.