there are two basic categories.. the plowhorse and the gazelle..
so the truly great can be either and it is not valid to compare
plowhorses and gazelles.
Jim Brown, Barry Sanders, Gayle Sayers, Earl Campbell,
O.J. Simpson are the best.
Guys like Dorsett, Thomas, Payton, were more longevity.
Tomlinson, Marcus Allen, Marshall Faulk, Jerome Bettis in there.
Emmitt Smith is a question mark how great due to the fact
he spent his years with probably the best offensive line ever
blocking for him.