Night flying sucks - even with the limited advantages it sucks, and by night I mean after midnight flying. I've at FDX but have a lot of close friends at SWA that love it. For me, I prefer FDX.

FDX - much more flexible in schedule (this may change now that we're in Flag ops but it still appears to be much more flexible), much more actual cool trips. Most SWA are pretty similar - doesn't matter how senior you get, the system form is very basic and similar. You can and will fly crap at FDX but you can also fly some very cool international - double deadheads in first class with long layovers in Hong Kong and Paris are not uncommon, 2 days off downtown Manhattan, etc. - won't get them every month but you can get them.

I come back from some grueling weeks at FDX but also come back with a lot of "what an awesome trip that was" - I rarely hear that from my SWA friends (all FOs, all mid-senior, and all based around southwest U.S.). Most of my SWA friends say they truly enjoy the job they are tired when they come home.

I differ a bit on commuting - unless you live in Memphis I think commuting is much easier with SWA - they have so many bases, most in great locations with a nice commuting policy and plenty of options. That takes away a lot of stress.

For benefits - no question that FDX is better in every regard, retirement, vacation, sick leave, disability, health care.

Great options though and I'm sure you'll be happy at either - you'll seek out what you like about the airline once you get there and concentrate on that.