Earl Campbell was a great HB. 5 Pro Bowls, 9400 yards rushing in his career, which was a lot for his time.
Barry Sanders was truly dominant. He played 10 years, and was in 10 pro bowls. He had 15000 rushing yards. 99 rushing TD's. He was the entire Lions team, and personally got them to the playoffs four times.
Campbell was a good player, but teams had to make special schemes to stop Barry Sanders.
He ripped huge holes in some of the greatest Packers defenses back in the 90s. In 1996 and 1997, the Packers had the #1 defenses in the NFL and I don't think Sanders ever got less than 100 yards against them--with a ****ty Detroit offensive line.
Sanders is my vote.