Who should i start at running back this week?

mcgahee or sproles. sproles in my opinion is better then ladanian but he has a tough def matchup. macgahee has gotten like 20 pnts each week and now is going to go against a easy def. clinton portis is going to go against the worst run def in the league. touhg desicion. either way you get lots og points but id go with portis for a chance at lots of pnts or mcgahee for a safe play of 15+pnts