I'm not sure Spiller can handle the workload as a featured NFL back....not very big and got banged up at Clemson. He hardly ever ran between the tackles, it was all outside foot races. He was only the featured back at Clemson for 1 season. Great all-around player though.
Ingram will be a solid back, but not a star.
I think Toby could end up being the most productive of the 3, on the right team. He could handle the pounding and is actually much more shifty than people expect/think. Ideal goalline back.