I think it depends on your mindset. I think Sproles is a safer play, less upside and more likely to pick up about 100 yds rushing and receiving combined. In a non PPR, that's 10 pts and pretty much a guarantee most weeks for him.
Bush has more upside IMO because of his receiving yards. Unless OAK can control the clock with the run (I seriously doubt it) they will be throwing all day and that should give Bush a bunch of looks out of the backfield. He is one of the top pass catching backs this year and I see him more likely to score than Sproles. However, OAK's Offense always has that bust factor.
Good luck. Mine:viewtopic.php?t=510694