At WR, I would definitely go with T. Owens. At RB, I would definitely go with J. Best.
That leaves M. Barber and J. Maclin for your flex. I believe having M. Vick at QB severely downgrades J. Maclin's prospects for production, while M. Barber should still see a significant amount of carries for Dallas. I would have to go with M. Barber.viewtopic.php?t=473797