Marciano, Hatton, Morales, Pacquaio, Duran, McCallum (Kalambay rematch), Jones Jr, Moore, Hopkins, Walcott, and Louis come to mind.
Tell me if this is wrong... Boxers from the 60s and 70s were the best feinters. Their feints just blended into their bouncy, rythmic movement across the canvas... Even the slight elbow twitches of Arguello seemed to cause utter hell for his opponents.