Napoles by a UD that's not even close. Wouldn't rule out a TKO either, as Napoles also had the firepower.
I like Napoles strictly on a styles match-up. Outboxing him is so difficult, his manipulation of range, his domination of the jab game, them aspects of his style are fantastic. He's slipping jabs and landing his own in centre ring all the time, and unloading off that as well. For me, someone like Basilio or Chavez (say at 135), would be bad for Napoles, fighters who really exert pressure from body strength, pushing him back and mauling him. I've got to talk about Floyd here too though, as a fighter i rate him higher than a lot of others it seems. He has versatility in my opinion, there have been some more complete technicians (Hopkins and Whitaker are examples), but there haven't been a that many that are outright better than him at what he does best imo. Mayweather is good at changing up a gameplan mid-fight. Judah is not on Napoles' level, but he showed in that fight he can become the pressure man when adaptation to that kind of gameplan is needed. I'm taking Napoles on the basis of the styles match-up though, he's such a great rong general that a find it hard to see how many fighters are going to outbox him, which at the end of the day, we can count on Mayweather trying to do.
Does any one think Floyd would take the fight in the first place? Napolese wouldn't just constitute a risk, he'd be the favourite.
Napoles, fairly easily. There's not anything I can think of that Floyd does better, bar handspeed and the 'shoulder roll'. Floyd wouldn't even fight him anyway. One thing that could happen is Floyds chopping accurate shots cut Napoles up, but barring that, Napoles wide UD.
If they were around in the same era, Floyd's "urge" would be vaporized into nothingness as soon as Napoles's name was mentioned. In a hypothetical match-up, I see Napoles winning quite comfortably. Like Fleaman says, he is better in almost every way at this weight. Wide UD, with a knockdown or two thrown in.