Dude,
Do you want an airline job? Take the one that's offered. Forget about who's hatin' whom and who's contract's better, so on and so forth. Take the job you're offered and build experience, then later you can be more choosy about the job you want to stay at (who knows, it could be Mesa).
I worked for Mesa for four years, commuted half that time and was never, not once, denied a jumpseat. In addition, not one pilot ever had the intestinal fortitude to say something to my face about the company I worked for. And if they had, I would have told them to go piss up a rope. A person isn't defined by the ID he wears. So take all the anonymous internet bashing with a grain of salt. You can do a lot worse than Mesa, believe me. You'll upgrade very quickly and life in the left seat is better than in the right seat, no matter where you're at.