If you want to fly only the 737, multiple legs/day in general, for your career; SWA.
If you want to cross the pond at 64N watching the auroras, enjoy pub grub and fine beers, and get paid for sleeping for hours in a bunk; AA.
As a new hire, I flew a 24 leg three day trip as a 727-100 FE. Decided I didn't like that at all - the extreme multi-leg stuff.
In seriousness, they both have positives. I found that I greatly prefer long haul, and it's nice to have a choice. I also found more than about 8 years in one equipment type bored me silly. It's nice to move around a bit.