Overall? Duran. Much deeper resume. Leonard had excellent quality but not that much of quantity in his resume. Duran had both
Leonard has wins over Duran x2 (top 3 lw, top 10 p4p), Hearns (top 10 ww), & Hagler (top 5 mw). The only 1 of Duran's wins that I would rate in that lofty company would be Leonard (#2 ww, top 15 p4p IMO). Duran has more depth to his resume, but Leonard has the better highlights IMO.
Leonard has better stand out wins overall vs Hearns, Hagler, Duran x2, Benitez, not to mention Benitez, Hearns, absolutely dominated Duran. But Duran has considerably more depth to his resume and some of his feats were better considering he was beating bigger opponents as the the smaller man. Leonard's best wins. Roberto Duran x2 Thomas Hearns Marvin Hagler Wilfred Benitez Ayub Kalule Donny Lalonde Dave Boy Green Armando Muniz Pete Ranzany Randy Shields 10 world title wins & titles in 5 different weightclasses. Duran's best wins Sugar Ray Leonard Ernesto Marcel Ken Buchanan Iran Barkley Esteban De Jesus x2 Carlos Palomino Pipino Cuevas Davey Moore Jorge Castro Vilomar Fernandez Guts Ishimatsu Hiroshi Kobayashi 16 world titles & titles in 4 different weightclasses. Up for you to decide.
Leonard. He beat an unbeaten Benitez,unbeaten Hearns, unbeaten Kalue, made Duran quit, beat Hagler who hadn't lost for years after being retired for years.