How about Joe Frazier at Heavyweight? Duran at lightweight Ricardo Lopez had a great uppercut at Strawweight..
Greg - that vision will NEVER get old. How do you score that? For Fury ? Against Fury? Or both, thus cancelling each other out, making no actual difference in the overall scoring. They do often say that fighters can be their own worst enemies - though that was an exceptional example of a fighter looking to defeat himself. Considering the positioning and awkward leveraging, I wonder if it would be possible to give yourself an uppercut and knock yourself out. Fury certainly gave it the old British try - chancing both his power and his own chin. Imagine contributing to your own, possible later life CTE like that? Drunk via your own punches. Even if I tried it, the small, self preserving voice in my head would always forbid me from going full tilt on my own chin.
Jack Johnson. It may sound overly bias toward the old timers but Lil Arthur had a high quality and very powerful uppercut. He needed next to no room to launch and land it. He also gave virtually no hint that it was coming, save for a slight wiggle of his hips to enhance it’s power - executed without changing the position of his feet/stance. Damn near ripped Jeffries head off every time he landed it.
Light Heavyweight Michael Spinks - Spinks had enormous power in both uppercuts and wasn't shy in throwing them.
Middleweight Still open. As a conversation starter it has to be said that Golovkin utilised uppercuts superbly with both hand and they were hard punches. Wasn't afraid to dig to the body either.