I can't attest to the other carriers mentioned, yet can give you my personal opinion of Mesa (as, unfortunately, I work for them). I commend you for doing research and soliciting advice...I only wish I would have been more thorough in doing so before I chose to work for the first company that offered me a job.
On the outset, Mesa may appear to be similiar to other regionals, but until you live our contract (or lack therof) you have little idea of just how much better life can be elsewhere. I know quite a few ex-Mesa pilots that were able to sweat it out here and get on with the big boys, yet considering the size of Mesa's pilot group, that's not unexpected. However, the turnover rate here proves that job satisfaction in an oxymoron.
I had little idea of just how poor our contract is...versus other carriers such as Comair, ExpressJet, just to name a few. However, here a just a few major differences that will give you a glimpse of what to expect. First, we get paid for segment times. For instance, if it historically takes, on average, 1:30 minutes to go from PHL to CLE, you get paid for 1:30...nothing more, nothing less Sometimes, you actually make it to CLE in less time than that, and so you actually get paid for MORE than you flew. However, oftentimes you WON'T fly under, or even come close, to the segment time, and that's where you get di**ed. Whether it's the endless wait for takeoff or getting a gate (PHL is a perfect example), or waiting out a ground stop (PHL again!) or that common hold due to traffic flows or weather, you get the same pay no matter what. Sound criminal? It is!
Another example are cancellations. We at Mesa don't get paid for cancellations due to weather, and oftentimes won't get paid for cancellations due to MX (the company has to meet a controllable completion factor in order for us to get paid for anything mechanically f**ed up). Try a year in PHL (or our new base ORD) and see how many cancellations you get...and subsequently subtract all that potential pay from your check. It's mind-numbing!
And, finally, just when you think it couldn't get any worse with regards to pay...you find that, once again, there is a discrepency in your paycheck! "How", you ask "can they shortchange me AFTER I wasn't paid for cancellations, and all those hours I spent without pay waiting for deicing, rampers to load my bags, gates to open up, etc". Well, they can, and they will!
Those aformentioned examples are primary indications of why you may want to re-think Mesa as a career move. Now, having said that, I can honestly say that I work with a fantastic, professional group of pilots. Here in PHL, we have a jet-for-jobs agreement with US Airways mainline furloughed pilots...most having upwards of 15 years experience at US Air alone! I can't think of how fortunate I have been to be mentored by such an experienced, first-class group. Unfortunately, with the pending merger, those J4J guys and gals may be gone...a travesty at that. Overall, the crews here get along great. It's almost as if with all the s**t we get from crew tracking, scheduling, and our crappy contract, we can all relate and make a positive experience out of what we CAN control. Maybe it's the old adage of "misery loves company".
The only other positive that I've found is the lack of time, personally speaking, of sitting on reserve. I spent a month before getting a hard line, and average around 80 hours a month (should be more than that in pay, but reference the above cancellation gripe). However, that's just my case...others have been sitting reserve for what seems like ever. And let me tell you, there is NO worse life that sitting reserve at Mesa!
So, overall, you make Mesa what you want of it. If you can stay away from the negativity of the crew room, look past the abuse you get from our pathetic contract, and appreciate the joy of flying airplanes, then it may in fact be something to consider. Personally, I tried that for as long as the kool-aid was being served, then I came to the realization that this place sucks. As far as the potential of getting PHX anytime soon, I would have to say that it would be a stretch. Our Denver base closed, and added even more pilots to an already senior PHX base. I'm closing in on my year, and don't even see PHX as an option for many, many months. And having said that, you could count on ORD or IAD as a newhire base (PHL as well, yet that will be short-lived). Mesa makes every effort to ensure trips start early and end late (thus eliminating commuting prior to show, or after release). And with minimized days off, I highly doubt you would see your home in PHX often.
So, that's my take. I wish you the best in your decision-making...it's not easy. As for me, like the rest of my classmates, I'm looking for another regional to go to. Live and learn I guess.