Thor,
Captain Tony above I think is at least partially right. However, you cannot really chase upgrade. I didn't take a job at Eagle in 2008 because I thought I was too old to be in for a 10+ year upgrade time. So I went to Chautauqua instead. Turns out Eagle would have been a far better choice. I would have avoided an 18 month furlough and would be a very senior FO now.
Bases are tough to chase too, but some are more stable than others. I personally would only consider Republic if you happen to live in Columbus, OH. or Indianapolis. If not, I would cross RAH off your list first. Also, our contract is about the worst in the industry and I don't see that changing anytime real soon. I think Skywest or ExpressJet are tougher to choose between. Overall, I think Skywest would be the better side, but where you live and your willingness to move plays into to it heavily.
Good luck.
-SR