I'd take either of them in a back up role. They are both experienced starters that could fill in if Alex got hurt. I think Orton has hit his ceiling and will only decline in the coming years, but Campbell might have some room to grow still. I don't think either are top tier QB's though and would not sign them to starter money.
Both guys should get some decent looks. Maybe a team like the Redskins, Browns, Dolphins, or Seahawks? All of those teams will be looking to upgrade QB via the draft and/or FA. I think Flynn to Miami is a given. Orton's best option man end up staying with the Chiefs.