Yes Forman ranks right up towards the top.
Also i'll give props to Evander Holyfield, after the Doctors diagnosed him with heart problems, he was written off by most experts. Ring magazine had predicted that the Tyson-Holyfield fight would be "fast and explosive-Tyson in One'. As we all know Holyfield dominated. And had a decent defense against Michael Moorer afterwards as well as superfights with Lewis.
Also Roberto Duran, thought to be shot, an underdog against the younger Davey Moore,(davey Moore had actually left During one of Durans fights (i believe it was on the Arguello Pryor undercard) because he looked so bad and the crowd was booing him. Few fights later Duran had battered Davey into a gruesome 8th round knockout. Sports Illustrated Headlines read: "Duran, One Mas Time, He that was lost has been found"