In my RB and RB/WR flex spots: Do I start Michael Bush, Marion Barber, Justin Forsett, or Mike Sims-Walker?

Bush is still questionable and McFadden is coming off of a great week where he will want to prove he's a producing option for Oakland. Barber is splitting carries with Felix Jones, who also happens to be starting for the guy in matched up with this week. Forsett has a lot to prove, and Denver has not been proven to stop the run attack yet. Sims-Walker has a lot to make up for, and I am very skeptical on him...I also have Bernard Berrian, but I will most likely want to see how he performs this week. Thanks for your input guys...