Depends on how old you are?

Younger I'd say AA for sure, with all of it's warts it has widebodies and mass retirements.

Older, it's a tougher call since you won't be a WB CA. If WB lifestyle appeals to you, then that's a factor since you can do WB FO. Lots of schedule options at AA. At AS you do have the option of shorter North/South legs in one or two time zones and some folks like that.

SWA is hard to say right now. In times past I would have put them before AS on the assumption that they'll soon get a contract but their historically good company culture seems well and truly broken. So uncertainty there and the limited schedule options would honestly have me choosing AS today. SW contract sucks and their management is doubling down on digging in their heels. They call themselves "plumbers" now because their CEO refers to them as "glorified plumbers"... even AA and AS management haven't quite achieved that level of toxicity.

I would have hands-down chosen SWA when I got hired back in the day (I actually had the choice) but it came down to driving to work. As it turns out I made a better decision then I knew at the time.

If you're older I'd still honestly chose based on living in domicile. If you're 100% flexible to move, then consider junior bases and where you'd really ENJOY living. Dallas, SFO, PDX, ANC are all very different. If you're in SOCAL you can work for almost any major.