Just a little more to think about, the retirement piece is correct from what I understand. There is currently a 12% "B" fund that is based on your income. Anecdotally, my friends who are UPS captains tell me that they make about 300K while the FOs are a little short of 200K. So there is an immediate 100K incentive to upgrade as well as the ability to hit the IRS cap for defined contribution plans.

For any RJ/MIL pilot trying to decide what to do, go for quality of life first. Money will be fine at all of the majors. If you want to live or are from a UPS domicile, go to UPS. Commuting adds to dissatisfaction at any airline. Good luck.