I think in every way by a little bit or a lot Robinson, I don’t believe Leonard is the 2nd greatest 147lber that can only be beaten by another guy named Sugar Ray.
Leonard only went to his left most of the time anyway from memory, not much at all I imagine, just thought I might point something of a little interest out because you mentioned footwork.
There's little difference between the two at their best. Robinson probably hit harder, Leonard may have been a shade faster. Robinson was more aggressive, and took more chances, thus he seemed to get hit more, Leonard seemed more controlled, and took chances when he had too. Both were in the masters class with skill level. Both were excellent athletically, Both could go the distance of 15rds at a fast pace. Robinson's consistency is legendary. But Leonard's competition over a shorter period was better than what Robinson faced at welterweight. They both faced and beat, different styles, They both had major "gut check" fights where they turned a potential loss into a win. I always lean to Robinson as the g.o.a.t, because of his consistency, he did it for far longer, in many more fights than Leonard did. However, if someone said they thought Leonard was better, I wouldn't argue with them because best night vs best night prime vs prime, he very well could be....
Harder to call than what it seems, Leonard's first loss had some factors of him not truly being emotionally stable(although I don't believe it),plus it was vs an ATG fighter that was like a more versatile but less stronger Armstrong. Robinson's first loss also came when he fought troubled inside the welterweight limit,vs middleweight Jake LaMotta who's also a pretty versatile fighter. I'd pick Robinson over 15 rounds by 2-3 points difference,but it's close,I can't imagine this super fight as a 12 rounder.
I don't think I can pick any singular attribute and say one of them is better than the other at it. But I do feel Ray Robinson could combine his defense and offense much better (similar to Jose Napoles) whereas Ray Leonard was typically doing either one or the other (at a very elite level of course). This could be the difference in a H2H fight - Ray Robinson staying more active and nicking some of the close rounds