I agree on the sentiment of Genaro. I always bring that up in threads regarding Mayweather's career. Genaro and the win over him is criminally underrated.
Oscar is probably his career defining fight as it really steered his career into what it is now. Corrales was a wonderful performance in his younger days. I voted Canelo though. So many here were claiming Floyd would never fight Canelo, blah blah blah blah. Floyd giving up more than a decade in age...and proceeded to dominate the younger fighter.