The 2nd deJesus fight should be in the running as well, no? SRL was his greatest victory, but ww was not his prime weight, so I'd go with deJesus III (although Palomino is my personal favourite to watch).
Duran is a mystery because of his performances but his prime was NOT in Montreal. I actually thought his prime truly began around the 2nd Dejesus fight and ended in the last of his lw days. I personally loved his performances against Simms & Cuevas though he wasn't prime at those weights. His peak years may have been 74-77.
Welterweight might not've been his prime weight, but he looked every bit as good against Palomino and Leonard as he ever did at Lightweight, in my opinion. For Lightweight performances, both the second and third De Jesus fights are surely up there. The second fight was Duran at his most "Duranish", though. The perfect mix of measured technique and savagery, whereas the third fight may've been his most controlled, aesthetically pleasing performance. The Villa and Ortiz bouts were very impressive as well.
Leonard 1 (on importance) then DeJesus 2 & 3, with Moore and Barkley up there (DM & IB don't rate with SRL & EDJ in talent). His fight with Hagler, very close going into the championship rounds, at his age, 25 lb's lighter than he was 5 yrs before, Hagler still had great victories to follow, is another grand performance.
I think Duran was at his most impervious in his third fight with DeJesus. I don't know if DeJesus had slipped any since their second fight, but I was amazed at how comfortably Duran handled him in every aspect in their third fight. One of the truly great perfomances by any fighter.
Duran vs DeJesus Trilogy Duran(1st fight) - 190,000 Duran(2nd fight) - 225,000 Duran(3rd fight) - 260,000 DeJesus(1st fight) - 220,000 DeJesus(2nd fight) - 200,000 DeJesus(3rd fight) - 170,000 Duran vs Leonard Trilogy Duran(1st fight) - 295,000 SSJ1 Duran(1st fight) - 2,250,000 Duran(2nd fight) - 280,000 No Mas Duran/Hercule(2nd fight) - 42 Duran(3rd fight) - 160,000 Ray Leonard(1st fight) - 280,000 SSJ1 Ray Leonard(1st fight) - 2,000,000 Ray Leonard(2nd fight) - 300,000 Ray Leonard(3rd fight) - 190,000