Thanks, it was hard leaving Iron Mike out of the top ten, BUT as TDTI and Riff pointed out, I too thought it was his level of bad opponents (era) that hurt him.
Just to show how close it really was for me, I placed Marciano over Hagler, Duran, and Sugar Ray because he was the only champion to retire undefeated in the heavyweight division and was World Heavyweight Boxing Champ from 1952 - 1956 with a 49-0/43 KO's (87.76%). Had he fought 15 - 25 more total fights, he may have lost a few and then may have dipped under Hagler, but not Sugar Ray at only 40 total fights (and some I dispute the W's).
Duran, had tons of fights like Julio Cesar Chavez, but I just can't buy into all their fights being 100% legit; somewhat like Tyson's. I always take flak about my stance on Ali, but 61 fights with 5 losses and only 37 KO's; surely ranks him, but I can't place him at the top. I really think his Parkinson's and political stances, and personality help bump him to the top of most lists, but mine is only about boxing.
Hell, at #10 I wrestled with all of the following (in no special order) and I am not sure why I selected Sugar over the rest. It really came down to him and Foreman at #10 in my mind; I really should have made it a tie with all of them. Oscar hurt his pro career (I think) by spending so much time at the amateur level: 223-5 / 163 KO's - another hard selection left out.
Oscar de la Hoya
Mike Tyson
Félix Trinidad
Bernard Hopkins
James Toney
George Foreman
Larry Holmes
Sonny Liston
Marco Antonio Barrera
Julio César Chávez (González) (legitimacy questions on many fights?)
Héctor Camacho (another with to many fight legitimacy questions)
Jack Dempsey
Roy Jones Jr.
Thomas Hearns
Jake LaMotta
Gene Tunney
BUT..... Sugar Ray Robinson at 85-0 / 69 KO as an amateur and 175-19-6 with 108 KO is the TOP rank. Even Ali himself said Robinson was the BEST!