Jc is what came to your mind first? what a nuthugger. JC is known for his workrate but never by his movement buddy.
Salvador Sanchez, PBF, SRL, Whitaker, Hopkins, Prime Delahoya, Prime RJJ, Prime Duran has good upper body movement, Prime Tyson, Prime Ali, Ricardo Lopez, Willie Pep...
I'd have to put Naz in there, alongside prime tyson- fair enough it got him into trouble but the sheer dexterity was sometimes incredible.
Tyson was a joy to watch in this respect at his best. Benn at his prime Hopkins Frazier Robinson Marciano