Ali. He called for the murder of blacks who dated and married whites. He did so openly, in an international publication (Playboy).
Exactly, unless you are a psychiatrist with access to the person, it is impossible to diagonise the illness. But as an eager amateur doing it for fun, Tyson does not strike me as a sociopath. He has had seemingly strong relationships and has shown in public an ability to show love. Duran maybe closer to one, Monzon too. Ali was not. Although you could argue he showed anti social behaviour, it was clearly controlled and often benefited him as a person to the rest of society.
Sociopaths are the ultimate self-serving narcissists. Their modus operandi is that if it serves THEIR good, then that's all that matters. They wear two faces, one is the charming, slick and manipulative one (think Ted Bundy or Charles Manson), the other is the perversely selfish and self-seeking one (not all sociopaths are murderers, btw). Kid McCoy takes first prize, imo. If you read about his life he shows all the classic hallmarks of it. Tom Sharkey once stated that McCoy would rather screw you out of five dollars on a scam that he thought was really clever than to have you give him a hundred for nothing.