The question is hard to answer due to the qualitative differences in the criteria of a "great victory". Perhaps breaking the question down into subcategories would be of help, and then comparing the results against each other. For example, Schmeling vs Louis I and Douglas vs Tyson are great victories as they were shocking upsets. Duran vs Leonard I, Greb vs Tunney I, and Whitaker vs Chavez are great because they enriched the legacy of the victor in a way few fights can.
Well that's the beauty, considering everything, what does the individual decide is the most redeeming qualities to look for hence the greatest victory in their eyes. For me it's a bit of everything.
ali v foreman buster d. v tyson leanard v hearns leanard v hagler what is hopkin,s win doing in there
Louis vs Schmelling II deserves a mention. If Billy Conn had beaten Joe Louis, that would have been No. 1.
1. armstrong ross 2. duran leonard clear top two for me because there are no excuses for the losers, then throw in some novel circumstances, supreme performances, and the high esteem the four fighters are held in! 3. greb tunney a shame we can't actually watch this one... still, tunney's only loss, and greb was at least ten pounds lighter, both fighters up there on the all-time great list. tunney went on to figure out greb... only makes this victory greater for me. 4. ali foreman 5. frazier ali you can always say that foreman was limited, but ali was the underdog at the time and the knock out was emphatic. for fight of the century you can say that ali was rusty, but the greatness he would go on to show during the rest of his comeback, coupled with frazier's convincing performance, make this a great win.
Ali over Foreman was a huge upset and a huge win over an aging, past his prime Ali. Douglas over Tyson was a bigger upset, but I think Ali's win over Foreman was more significant. Ali past his prime beat a prime, undefeated powerhouse like Foreman while I don't remember a past his prime Tyson beating anyone significant.
I put hopkins in just so the current era had a fair mention lol. I've seen a lot of valid points and I still think that beating a prime sugar ray leonard is as good as it gets.
Better quality opponent? No contest. For me the circumstances 4 Duran-Barkely make it, imo, his greatest win. 37 years old, former LW & 5'7 up against a big, 6'1 hard hitting MW in his prime, who recently beat Hearns. Duran couldnt stay outside, he had to engage Iran up close & he did. He took huge shots but just kept on going, even KDing Iran in the 11th. I love that fight.