Jim Brown is the consensus pick of most experts as the greatest running back in NFL history. I, myself, never witnessed Brown work his magic on Sundays; for those players, see Vol 1 and 2 of The Great Running Backs. Brown gets one of his own. A remarkable blend of power, speed, desire, and elusiveness was #32.
Sanders and Sayers could both cut full-speed on a dime. Human highlight reels, and 2 of the 4 greatest backs I’ve ever seen. See Vol. 1.
See Campbell video here.
The two greatest running backs I have ever viewed, Earl Campbell and O.J. Simpson. Both combined speed and power with an uncanny, innate sense of how and where to maneuver. Like Larry Bird or Steph Curry in basketball, it was as if they were prescient, seeing how all and everything was developing just a shade before the other players.