Which of these running backs should I keep?

Since this is a Keeper league, I would keep McFadden. Last year was a tough one fantasy-wise for McFadden, the Raiders had no ping attack to speak of so opposing defenses could key in on the run and force JaMarcus Russell to beat them. Justin Fargas also had a solid year on the ground, forcing McFadden to share carries in the Raiders backfield. The bottom line is that McFadden is a rare talent and eventually will be an every down back in this league and the future of the ground attack for the silver and black.