in no particular order since its insane to try...

Gatti
Duran
split between.. toney/roy jones..even though both have been on top of the game for years both have recieved
mad amounts of criticism from the press about wieght/ who they fought...
james faded out for a few years and came back to become fighter of the year and hes still up there trying to prove hes the best...
roy lost three times strait, knocked out twice, and is still fighting trying to get back his titles..
Felix trinidad.. i personally feel he has great heart ( much like alot of great puerto rican fighters)
because he always fought hard, fought for the entertainment of his fans, took his first loss at the hands of bhop, and was up at the count of nine but the fight was stopped in the last round..
and he came back to fight mayorga more then anything because he missed the roar of his fans...

i have to put oscar up there too because hes always been among boxings elite and always fought his heart out and taken the comptetition that he should have whilst on top,
he had a long struggle with fans but he kept fighting and won them over...
he took his defeats with grace and hes still doing great things for the sport of boxing..

of course honourable mentions go to ali, frazier, bruno ( the brain might not have been there , but the heart was!)
urrrr... im going blank.. but good sujestions from you all already!!
Peace