I'm always amused by this. Perhaps more than any other sport, football is played as a team. Yes, there are those among them who are truly the best of the best, but deciphering them from among this list is pretty silly. How on earth could we know how Barry Sanders would do behind the Badger offensive line, and with the Badger play calling of 2014 (or whenever)? Or vice versa.
I like the Badger backs. We've had several elite ones. But more than that, we've had several elite running teams. I'm fairly sure that Darren McFadden, Bo Jackson, or Charles White would have had amazing numbers for a modern era Badger team. Not to take anything away from Gordon, Ball, Dayne, or Taylor--all fantastic backs. But who's to say who was better? All you can do is pick your set of statistics, and go with that (and remember that you are rewarding the offensive lines, and offensive systems as much as the individual backs).