The one that calls first?
*I know, I know, that's no fun.*
Eeeeeeeyup!
The industry is in a semi-temporary "boom" but there will absolutely be periods of boom (now) and periods of bust.
A couple "old man" points:
a. Never choose an airline because of their bases. They open and close with regularity, especially secondary bases. AMR will probably always be in DFW, UAL will probably always be in IAH, Delta probably isn't leaving ATL but exactly everything else is in limbo. DO NOT FOOL YOURSELF.
b. Money comes and goes as well does contractual language. The grass is always greener. It is.
c. Personally, I'd suggest trying to find a social "fit". These are going to be your coworkers for the rest of your career. You're going to have to fight with them and fight for them, but it always has to be what's right without respect to your ego. But there's no way that you, on the outside, are really going to be able to determine that.
d. Fleets? Forget about it. It's porous. "AMMAH FLY THE (whatever) TILL I RETAARRRE!" — ha! Unless you're five years from retiring, you can forget about that idea. I'll be in the single-digits when I retire so some of my copilots say "OMG! You'll be a 777 captain!" Crap, in the mid-2030's, if the coolest thing we have is a 45 year old 777, well, "Woo."
e. Routes? They come and they go and they change.