I'd usually go with the safer play in Graham because he should be pretty much an every down back and even if behind will catch balls. But Torain does have potential, medium risk/high reward as opposed to low risk/med reward in graham. I'm a risk taker so I'd go Torain. Hell I think you just convinced me to start Torain over Sproles.
1QB, 2RB, 2WR, 1 WR/TE, K, DEF
Standard 12-Man Auction League
QB - C. Newton, J. Flacco
RB - R. Rice, M. Jones-Drew, M. Tolbert, C.J. Spiller, D. Karim
WR - L. Fitzgerald, W. Welker, J. Graham, L. Moore
K - S. Gostkowski
DEF - Jets, Titans