REALLY tough to say, but I think probably Pryor. The 17-year-old Benitez that beat Cervantes was a true phenom, but I don't even think he had peaked yet. I think he peaked a few years later at 147 against Palomino. Still, even that 17 yr old Benitez was so good that beats MOST junior welters in history, but probably not Pryor. I love both these guys, so its hard for me to make a pick. I think the Benitez of the Palomino fight was better than Pryor ever was, but that version of Benitez was a welter and not a junior welter.
Just rewatched BOTH the Cervantes fight and the Palomino fight. I must say, there aren't too many 140 pounders I'd take to beat Benitez. Even at 147, outside of a few guys, most wouldn't beat Benitez at his best. Pryor would have the best shot at 140. He could cut the ring like no other. Close one to call. Could see Pryor pulling out the decision, then a rematch with Benitez making the adjustments and taking the W.