For me, pretty much Joe Louis....great at timing his punches, finding his range, landing clean with power, great killer instinct....dude was an all around great fighter.

But if we want to do this Frankenstein Boxer let's see.....

Featherweight-Lightweight: Defensive stylings of Pep/Whittaker, killer instinct of Duran, power and handspeed of Mosley

Welter-Middleweight: defense of Floyd Mayweather Jr., power of Tommy Hearns, ring generalship of Ray Robinson, handspeed of Ray Leonard

Supermiddle-Light heavyweight: from what I've read either Sam Langford or Harry Greb...but if not those guys then the defense and chin of James Toney, the speed and power of RJJ, and the ring generalship of Bernard Hopkins

Heavyweight....just Joe Louis