Mike Tyson and Donovan Ruddock had some serious leg strength behind their uppercuts. Other then that Floyds right hook to the body and then sneaky uppercut is amazing.
If we're talking about former fighters as well as present day ones, then I would say that Hamed had an underrated uppercut. He would crouch down and then spring directly up into a sort of corkscrew uppercut, with all the power coming from the legs. When he missed it looked sloppy and threw him off balance, but when he connected it looked pretty damn hurtful.
JMM and Bute Not saying he is close to the best upper cut boxer around today, but Josh Clottey, when he's not in "100% Punching Bag" mode, can throw some good uppercuts.
The sexiest uppercut is Judah. JMM's uppercut is a bomb every time. Didn't he catch Pacman with the uppercut in their 2nd fight. Had pacman make the oh **** face lol.