A lot of people chased the 2 year upgrade a few years back and ended up stuck or furloughed from places like TSA, PSA, and Republic. Go for the airline you can stick around for and be relatively happy with.
Republic isn't the worst place to be but it's not the best, either. I don't work for SkyWest, so I can't tell you what life is like there...but I would think commuting out of LAX makes this a win for SkyWest.
Good luck!