I find it so funny that people who have never worked at either of the two find it such a bad place to work. I left an RJ operator out of ATL for a Gulfstream Captain job. It's not all that bad here. Training is long, but I was able to hold a line right out of training, and am enjoying my 16 days off this month. I'll be flying 95 hours this month and will have no problem getting 1,000 hours PIC within a year.
At Mesa you'll be an FO for 3.5 + years (at least that's what another thread is saying). In that time you can get plenty of PIC time and move on.