Sam Bradford, Kyle Orton, or Jason Campbell for Fantasy Football?

So, I'm in a Fantasy Football league and I picked Peyton Manning as my QB. Peyton Manning looks like he'll be out week one, so it leaves me in a bit of a bind. I'm just looking for some opinions on who I should start for week one.

Sam Bradford is currently on my bench as a back up, and the only reason I don't immediately choose him is because he's going to be up against the Eagles Defense.

Kyle Orton is a Free Agent and will be up against the Raiders Defense.

Jason Campbell is a Free Agent and will be up against the Denver Broncos Defense.

I think out of the three, the Raiders have the most offensive weapons. I know that none of the teams are to "hot" but this is what I have to choose from. I'm just looking for some opinions.