I think your underestimating Pancho a bit. I know you rate Canto higher though. And he was a magnificent boxer with an outstanding defence, but Pancho was pretty relentless. I would still edge towards Canto though I don't think it would be as one-sided as you suggest.
It's more of an era by era thing, what with the modernized game in comparison to the general time period Villa fought in. Baed on greatness for their era, I make no seperation, but head to head I do.