Another consideration is your long term plans for travel (especially if you plan international travel in the future) and how an airlines frequent flyer program might fit these plans.

I do not live at a hub airport and could have picked AA, CO, UA or even DL. I chose AA because I will have 2MM before I retire and will have Platinum for life. A key aspect of this is that AA counts all my miles (including credit card charges, dining program etc) not just EQM towards the 1 and 2 MM awards. This may or may not be important to you.