I'm with a regional and have been tempted with a couple corporate/91k/fractional opportunities that would be much better in the short term, but those mainline pay scales keep luring me to stay. Then again, I could never reach mainline, so it's a tough call. Over the course of a career, it seems like a 121 pilot might earn more, but corporate has other things to offer that can be a better fit for some people. I've heard stories of non-121 pilots making the jump to mainline carriers, but no specific examples.