JMM. His lead left uppercut, and left uppercut i general, was a thing of beauty. Up close or not he could deliver it with precision, venom, and on its own or as a combo. JMM had it perfected!
I seem to remember him picking some beautiful left uppercuts against Watson (both fights), Collins (both fights), Thompson (both fights), and Cronin (in a small leisure centre in Splott, Cardiff).