Tough call, those are all good companies to work for and since you are willing to move that makes it even harder.

Is there a particular type of flying you would like to get into? Eagle ATR turboprops island hopping through the Caribbean? Skywest west coast lifestyle? Winter sports in MSP/DTW with Pinnacle?

The majority of the regionals offer roughly the same path at this point. Gone are the days of the super fast upgrades at XYZ carrier, or decade long upgrades at Eagle.

But as someone else said, go through the interviews and see which ones hire you. Also take the interview as a way to gauge how you would like being a part of that company. Get a feel for the corporate culture, ask questions in the interview, etc. Good luck!