At some point the money doesn't really matter anyway, so you have to look at every other factor in making the 91 vs 121 decision. Domicile, days off, benefits, etc. These things are readily available online for all the airlines, but a little more difficult to figure out for a 91 department, but not impossible. It's the intangibles that are important in corporate (management style, off duty expectations, department culture, job security) that are so darn difficult to pin down before one actually starts working for said department. Don't be fooled by the size/number/newness of the planes, the size/name recognition/stock price of the company. You will never know what you have gotten yourself into until you are there. At least at the major airlines you have a pretty good idea of what to expect.