Obviously someone in JDfly's situation should look at as many aspects of the regionals he's looking at as possible. It is important to have a Plan B and a Plan C if, as has been mentioned here and elsewhere, the music stops and he gets stuck at whatever regional he's at.

Those other factors -- upgrade time, pay scale, other benefits and bonuses -- are important to consider, they are just secondary to the main QOL threat that he's most likely to face (base location, and thus commute difficulty). If the basing/commute is pretty much equal between two carriers, then the 2-year or 5-year pay and progression outlook should be a tie-breaker...but not the other way around.