that's a tough call. gotta remember that keith has gotten goal line carries recently, but panthers run defense is pretty good. i expect davis to have more yards, but keith to have a better chance at a touchdown in the redzone.
You should always start RB's before your recievers if you can. Keith looks to get 10% of the touches vs. Carolina and probably a TD, still doesnt look like much yardage for your fantasy team. I think Davis since SD has shown signs of weakness in their secondary.