I voted for Douglas v Tyson. Leonard v Hagler Laing v Duran Honeyghan v Curry Spinks v Ali Rahman v Lewis Braddock v Baer All above worthy of a mention.
I'm going Fitzsimmons vs Corbett. Leonard vs Hagler is up there as well. Out of those listed I'd have picked Duran vs Leonard.
Foreman v Ali Frazier v Ali fight I Ruiz v Joshua Rahman v Lewis I Lewis v Rahman II Tyson v Berbick Holyfield v Tyson I Fury v Wilder II Hagler v Hearns Hearns v Duran Foreman v Frazier I & II Foreman v Lyle Lewis v Klitschko Holmes v Cooney Spinks v Holmes I Tokio D. v Tyson
Braddock / Bear Turpin / SRR Shibata / Saldivar Braxton / Saad Buchanan / Laguna Stracey / Napoles While not the " Greatest ever " seen as major upsets . keep well.
By definition, the greatest win in history should be the one who overcame the biggest odds. So Douglas over Tyson. Can't say Duran/Leonard because Duran wasn't a 50-1 underdog or whatever Douglas was.