Those would be my top three as well, although it would be difficult to pick an order. .....Holmes could also be up there.
Top three Heavyweights of all time:
1.) Muhammad Ali-- a three-time champion who held the belt for all but a handful of years between 1964-80, Ali left his mark on the sport as no other figure has before or since. Witty, Brash, tenatious and almost superhumanly controversial, the former Cassius Clay might just have been the MOST important sports figure of the mid-twentieth century, taking his battles from Joe Frazier to the Supreme Court and back again.
2.) Rocky Marciano-- Gotta give some love to the ONLY man to ever retire the Heavyweight title undefeated and untied in his ENTIRE professional career. 59-0 speaks for itself, and Marciano had the good grace and intelligence to bow out when he finally got tired of his excellence. A good man as well as a good boxer.
3.) Joe Louis-- An Alabama boy's just got to stand up for the Alabama boxer who made good...REAL good. The Brown Bomber stomped through the '40's like a panzer blitzkrieg, but he stood up for what was right in a time of racial divisions and bigotry against black sportsmen.