Ball/Richardson (can't pick but I think BOTH are products of the line, system, and tons of carriers against weaker teams, not pure talent and value to team)
Ball's numbers against inferior competition:
UNLV - 10 carries for 64 yards and 1 TD, 2 Rec. 67 yards 1TD
NIU - 20 carries for 91 yards and 2 TD
South Dakota - 15 carries for 89 yards and 2 TDs
Indiana - 14 carries for 142 yards and 3 TDs
In those four blowouts, he had 59 carries (averaged 14.75 per game) and 386 yards (96.5 yards per game).
Other large score differential wins:
Oregon State - 18 for 118 and 2 TDs
Purdue - 20 for 223 and 3 TDs
Minnesota - 23 for 166 and 2 TDs (plus 1 Receiving)
Against the good defenses/teams:
Nebraska - 30 for 151 and 4 TDs
MSU 1 - 18 for 115 and 1 TD (plus 1 receiving)
OSU - 17 for 85 and 1 TD (plus 1 receiving)
Illinois (great run defense) - 38 for 224 and 2 TDs (plus 1 receiving)
PSU - 25 for 156 and 4 TDs
MSU 2 - 27 for 137 and 3 TDs (plus 1 receiving)
Ball got his against good competition. He was limited on carries early against lesser teams. He played well against all the best teams he faced averaging 144 on the ground and 3 TDs in those six games.
His numbers more than make his case.
That said, in an unbiased vote, mine would go to RG3 with Ball a close second. The other three would be far behind those two.