Look at the retirement numbers for both, it's broken down by year on the APC airline profiles.

Try to get some insight on base seniority... not just to get into the base, but how senior it is moving up through the ranks. Some bases can be easy to get into, and maybe have OK progression as an FO but you hit a brick wall for upgrade. Variety of reasons, such if a base is a nice place to live but expensive, junior FO's may not want to be there but CA's can afford it.

Consider likely growth... historically SW has beat AS on that count.

If you live in base, the trip construction doesn't matter that much but at SWA you're going to be doing either am or pm, and usually lots of legs (and get paid more to do it). At AS there are some cush schedules with some seniority... some folks like QOL on the road, 24-30+ hour layovers in resort destinations, others prefer to work hard at work and be home more.

All else being equal I'd take SWA.