I'm in the same boat, so I'll be monitoring this thread. I have Felix Jones, Jahvid Best, and Frank Gore this week and have penciled to bench Gore this week.
The Dallas front seven is better than its secondary and the Niners offense are a run-first offense (thanks to Alex Smith being way too conservative in the passing game). I see no issues for Dallas selling out to stop the run this week and make Alex Smith beat them on the air attack.
Go with Best because his matchup is better, esp. in PPR leagues.
14tm. PPR+IDP+return-yds. league
TE-Finley K & IDP-[streaming]