135 would be better. Chavez as the underdog was a better fighter at 135, and Duran may of got even better in that 78-80 period when he left the 135lbers.
Given the fact his 135lbs resume is comparatively weak, the only way Duran could objectively be ranked over Leonard or Gans is if he was a good sight better as a talent; as it is, both Leonard and Gans are generally held in higher regard as lightweight fighters than Duran is. Naturally, all opinions rest on an unstable foundation of preference, but as compiling lists go, Ted Spoon finds that Duran fits nice n' snug in the third spot.