I think you have to have definitions. If talking career, guys like Emmitt Smith look good and Sayers isn't even a consideration. If talking "best RB for a single season" a lot of other guys like Sayers are possibilities. Sayers had two great years in 1965 and 1966, then injuries wrecked his career. Emmitt tops your RB list because he strung together great season after great season after great season for a decade. Brown is hurt a bit because he ended his career prematurely to be in the movies, retiring when still the best back in the NFL. In fact his best total rushing yardage was in 1965, the year he retired at age 30.