For me, it'd probably be a toss-up between Brown and Cartwright, assuming Forsett isn't at 100% (which would give Mora the perfect excuse to have Jones handle more of the load; still not sure why they're clinging to the idea of him as their prime RB).
Brown gets a big bump with Slaton out, but he'll generally only get points if he can catch, as Houston isn't much of a traditional running team. Plus, Jacksonville's pass defense is pretty bad, meaning Schaub will have even more incentive to pass all game.
Then again, Cartwright takes a hit because Washington will likely be playing from behind against the Saints most of the day.
If your league's PPR-heavy, maybe go with Brown and hope he gets a lot of short dump-offs from Schaub (ala Slaton the past couple weeks). If not, I'd say ride Cartwright and his (relatively) guaranteed workload.
(0.5 PPR, 12-team league)
QB: Vick, RG3
RB: McFadden, Matthews, K. Smith, R. Williams, M. Goodson
WR: Nicks, S. Smith, Britt, LaFell
TE: Hernandez, Pitta
DEF: Spot start (Cin in wk4)