Eagle: REALLY long upgrade time, probably career dead-end, low pay, good benefits, lots of bases.

Pinnacle: Potential downsizing due to NWA BK reorg. I suspect they are hiring only to replace the rats who are abandoning the sinking ship. All-around crappy place to work.

PSA: Don't have too many details, but talked to a buddy who works there today and he said he's getting treated like crap.

Air Whiskey: Historically a great place to work, it looked like chapter 7 for a while after united terminated them, but they paid USAir $125M and landed on their feet with a new partner. Since it's a good place to be, upgrade could take years.

XJT: Historically a good place to work, but CAL will probably reduce their flying by 69 jets in 2007, in which case they could operate the jets for another partner OR return the jets to CAL and return 450 pilots to the streets. If you go there you might get lucky or you might get furloughed.

Mesa: Historically crappy work rules, labor unrest, and medicore pay. Rapid upgrade opportunity, largest regional jets in the world, lots of bases. Contract is up in 2007, so things might improve.

My best guess depends on what you want out of life:
Stability at a good company: Air Whiskey
Career Progression: Mesa
Some of both: XJet, but you're taking a chance.

Actually I would recommend Skywest, but I doubt your times would qualify.