Ok, looked at some of the top RBs.
Barkley and Guice are pretty similar. Both are slashers, kind of in the vein of Clinton Portis.
Bo Scarbrough looks a lot like Chris Henry... not very quick to get going, but he's very tough to bring down and has a nice top speed.
Royce Freeman has extremely impressive vision and uses blocks very well. He's not quite the athlete that the other guys are probably, but that's a skill that will translate very well. It might just be a flexibility issue with him -- if he can loosen his hips, he might find extra speed.
Ronald Jones II will be fun to watch. He reminds of another Jamaal Charles but with perhaps more ability to run inside. He's also only like 20 years old, so who knows how much more his frame might fill out. He's the best playmaker of the bunch though. If you feel that Reggie Bush came to the NFL about 10 years before his time (before the NFL adopted a more pass-first mentality with wider formations), then Jones II is your prototype back. He actually hasn't caught the ball much out of the backfield yet, but he seems to have good coordination and thus the potential to.
Rawleigh Williams III might be the best everydown back that I've seen yet. Very stout and quick, sort of like a Ray Rice kind of back. Good vision, smart cuts. Unfortunately, I just read about his serious medical concerns, and there's even talk he may retire at this point in his career. That's pretty much a no-go.
Mark Walton looks solid. Similar style to Rawleigh Williams but not as good.
Kalen Ballage looks pretty good. Power and speed. A little tall, but he runs with a good pad level inside. Conservatively, you could say Matt Forte, but there are bits of Tevin Coleman and David Johnson too.
I watched tape of probably 10 other guys that I was less impressed with.
My top backs would probably be Kalen Ballage, Royce Freeman, and Saquon Barkley.