Maybe Camacho (either one) or Panchito Bojado. The more I think about it, the more I think boxing doesn't really lend itself well to sociopaths because of the training camps. Enduring long training camps doesn't seem like something that a person who displays impulsive behavior would be able to successfully spend a lifetime doing.
Lamotta, Galento and Sullivan were mostly likely suffereing from some anti social/socio/psychopathic personality disorder.
Dunno about Duran, he gave away most of his money just by handing it out to people in his neighborhood. Ray Robinson seemed to act like one at times. John Garfield said Ray didn't even care when he killed Jimmy Doyle and Ray only pretended like he cared.
Duran was/is not a sociopath SRR cared from my perspective about Doyles death. It changed how he did business in boxing and he started backing out of fight after fight