In my entirely biased opinion, the best RB ever has to be John Riggins.

Never mind the impressive stats, the 4th and 1 game winning run in Super Bowl 17, the Hall of Fame career, the following vignette illustrates why he was one of a kind.

At the 39th annual Washington Press Club “Salute to Congress” Dinner in 1985, Washington Redskins running back John Riggins was seated at a table with Supreme Court Justice Sandra Day O’Connor. As usual, he had not missed attitude adjustment hour. Sometime before he passed out under the table, he managed to respond to what he considered boring dinner conversation by giving some advice to Mrs. Justice O’C. “Lighten up, Sandy baby,” he said.

(Some accounts of the event allege he actually said, “loosen up,” but the difference may have been unable to detect, given the quality of his diction at the moment, and it’s a cinch Riggo himself doesn’t remember.)

link to article not about Riggins, it just opens with the story)