Interview job offer advice   

I agree with Old Guy. 

Also don't be afraid to tell the job you'd prefer that you have an offer for "X" from a different opeator.  Don't say who exactly, but don't lie about it either.  It's a small world and folks at the different places all know and talk to each other.  (I still get calls and emails asking about pilots I might know and I retired 3 years ago.)

Tell the folks where you want to work that you'll take the job if they are willing to match the better offer.  You do run the risk of them saying "see you later," but maybe not. 

Good luck!