Getting into this topic late.
My 2 cents are:
Barry Sanders was the more talented athlete, but that is about it, and better athlete =/= better player ***coughDeAngeloHallcough***.
Consistent running backs generally contribute (simply from running, not even considering blocking etc.) more to the offense than boom-or-bust backs with similar or even somewhat superior stats. Barry Sanders was probably the greatest boom-or-bust back the game has ever seen, but I would still only put him as borderline top 10 all time.
My take on some other commonly seen arguments:
The 'Sanders quit on his team' and 'Sanders was awful in the playoffs' arguments are just Cowboy fans blowing smoke to excuse Barry's superior conventional statistics. Stop doing it; you don't need to.
The 'Emmitt had the greatest oline ever, while Sanders had a cruddy one' is a large exaggeration. Nobody puts up Barry Sanders numbers behind a weak oline. Also, I think the early 90s Dallas line is a bit overhyped, and probably Smith & Aikman made it look better than it was. It was still excellent, but not the greatest oline ever like many people make it out to be. The oline gap is much, much smaller than most people seem to think.