Who would you considers the "nice guys" of boxing who were true gentleman and sensitive, selfless men outside of the ring, or at least very friendly towards the fans.
Here's some of my picks, but I'm sure there are hundreds.
Joe Frazier (not entirely sure of his conduct out of the ring but a true gentleman within and rarely fouled which indicates to me a strong character and sense of honor)
There's so many that I don't think I could possibly do it justice myself. Lots of great guys in boxing. I personally think boxing has seen some of the kindest, strongest (in regards to character) human beings of any sport.