Napoles by a close majority decision, being a bit smoother than the Kid, but it will come down to the final two rounds of the fight.
I've always liked Gavilan in this one, based on his height and reach advantages and better all-around speed. Plus Napoles was a bad bleeder (which certainly doesn't bode well against as sharp a puncher as Gavvy), and Gavvy proved himself against a better and deeper level of opposition that Napoles did.
I like Gavilan for the reasons M2S gives, but I don't see this being anything but razor close, even if they fought 100 times.