I'm going to give a very personal list of the best running backs I've seen. Yes, I'm sure some of you won't like it, because it's based on single seasons of play, and I'm going to list 4 running backs.
I'm not going to rate running backs I've never seen play. That means people like Jim Brown, Marion Motley, Lenny Moore and Gale Sayers aren't on this list. All the lists I've seen so far have no real ranking of running backs prior to 1965 that I can see; and it's just my opinion but if you're not considering Jim Taylor and Doak Walker among the best you're just kidding yourselves.
I'm not going to rate players I only saw in ESPN highlights or NFL Films. This affects Bo Jackson and OJ, and probably most importantly Eric Dickerson.
This is an area where, if football acquires the equivalent of sabermetrics, it would help. I'd love to see Jim Thorpe's peak running skills normalized to a modern era.
In no particular order:
Terrell Davis - His single season best is the best running I've ever seen by any running back, period. That his line was as responsible for it as he was is almost certainly true, but his high water mark season has to be marked with double exclamation points.
Earl Campbell - There are a couple seasons at his peak that are almost interchangable, but the night game were he ran over, around, and through the Miami Dolphins made a huge impression on me.
Franco Harris - Why? I've never seen anyone do to Tom Landry's defenses what this guy did. He single handedly destroyed a defense whose modus operandi was to stop the run. He was a big game player who always performed, and it's sad the way his career ended.
Emmitt Smith - The New York Giants game. If you're a Cowboys fan, you know what I mean. Just how many yards did he gain on a dislocated shoulder? How many? How important was that game? At his peak, this guy was the best money player in the game.
The near misses:
Eric Dickerson - didn't see enough of him to get any feel for his skill. Then again, I would turn the TV off rather than watch Eric at his peak.
John Riggins - A strong candidate for the 5th spot. He had some absolutely destructive moments in big games.
Tony Dorsett - Another strong candidate for the 5th spot. Terrific outside runner and underrated in the middle of the line. I promise you the 99 yarder against Minnesota wasn't a sweep.
Walter Payton - I didn't see a lot of Sweetness and his problem is that his team, Chicago, wasn't a good team (and therefore on National TV) until near the end of his career. This is a guy that deserves more tape study.
Bo Jackson - Another player I didn't see a whole lot of. Is he a candidate? certainly, but a few snippets on ESPN isn't enough for me to form an opinion of him. As an aside, I think it's hard to consider Bo a great runner and ignore Terrell Davis..
O.J. Simpson - People just don't put together 2 200+ yard rushing games at the end of a 14 game season to get to 2000 yards. I'm going to plead guilty to the 3-tv-station only rule here. Yea, I saw the highlights and read the results, and they certainly are phenomenal. But the Buffalo Bills didn't get much airtime in Haughton, LA.
Jerome Bettis - One of the best college players I ever saw. I just hated what his Notre Dame squads would do with him. Didn't see a lot of him in the pros but the Bus was a fine pro player as well.