Jim Brown, Emmitt Smith and Barry Sanders all got together at a massive autograph signing event over the weekend -- and it begs the question, how do you rank these guys!?

All 3 have routinely been brought up in the age-old "Who's the greatest running back of all time?" debate. They're all in the Hall of Fame. They're all legends.

So, when they got together for a pic at the Chicago Sports Spectacular, it forced us to do some real debating in the office.

Barry Sanders ... 15,269 yards on the ground in just 10 NFL seasons. 10 Pro Bowl selections. 6-time All-Pro. All this without a great offensive line.

Emmitt Smith ... 18,355 yards rushing in 15 seasons. 164 rushing TDs. 1993 MVP, 3 Super Bowls, 8 Pro Bowls, 4-time All-Pro.

Jim Brown ... 12,312 yards rushing in 9 seasons, 106 rushing TDs, 8-time NFL All-Pro, 9 Pro Bowls, 3 NFL MVPs.

We looked at the autograph prices this weekend ... here's how they stack up in terms of value.

Barry Sanders ... autographs start at $135, photo ops are $135.

Emmitt Smith ... autographs start at $235, photo ops are $200.

Jim Brown ... autographs start at $150, photo ops are $150.

So, go ahead ... rank 'em.