I'm glad Napoles has been mentioned a few times. Jofre too. They were as skilled as any fighters there have ever been. Robinson, Charles and Pep are more obvious picks maybe but in terms of completeness of their skillsets Napoles and Jofre are equally worthy of consideration.
Great shout with Samart. One of the best 'stand up' martial artists of all time. At his peak he never gave opponents the same look; always adapting to their styles. Brilliant stuff.
Also, for me, Harada is sold very short skillwise. One of the best jabs ever, and the most technically skilled swarmer IMO.