I'm old enough to know that ya just gotta go with James Brown. Hell, if he'd stuck around until he was too old to play any more like some of these guys, they'd still be chasing his record, which, remember, was set in the days of ten games a season (assuming my memory is correct, always a shaky plan...).
But number two? Hey, knock his trial, his "acting" and anything else, but in my book, O.J. is definitely it. The Bills never had shit other than O.J., and still no one could stop him. Hell, the only reason the L.A.P.D. caught him is he just plain forgot how to run...