Sayers was magic as well...more fluid and spindly than Sanders, but very similar in that they just needed a small opening and then were gone. There a ton of great Sayers runs and returns, and the amazing thing to me is that all those clips are from essentially a 5-year period. The difference between the two IMO is that if you watch Sayers, every move/fake he makes is done while his body is moving forward. Sayers is always running toward the goal-line. Barry is more of a stop-start guy, who would shuffle side to side before hitting the hole (Franco Harris would actually do this, too, but he was a bigger, slower RB).
OJ Simpson was a big RB at 225 lbs, and what people forget is that he was the fastest RB to play the game. I think he and Herschel Walker had the fastest 100 times of any RB ever, and Walker wasn't nearly as elusive as Simpson. Simpson was the total strength/speed package.
Bo Jackson was awesome. He would be a good top 10 choice. Dickerson was very productive, but he fumbled a lot and just wasn't very "distinctive". Maybe I'm selling him short. Faulk was a great all-around RB, but not in the same "runner" class as the other guys (if that makes sense). Terrell Davis was one of my favorite, but he always seemed like an effort guy. Not super fast, not super big, not super elusive, but very tough and always gave 100% on every run.