First job out of college...I was based in KC and got assigned a project in Chicago.

Project was in the northwest 'burbs, so that ruled out Southwest and Vanguard (yeah that was a thing back then).
That left UA and AA.

UA flight left MCI at 6AM on Monday.
AA flight left MCI at 6:30AM.

I wanted the extra 30 minutes to sleep. On the first flight, an FA handed me a paper form to join the program.

So I joined AAdvantage, and have about 1.7 million LT miles. They became my go-to program for 20+ years, and have only really fallen in favor with me in the past few years now that the airline lags its competitors in so many ways and AAdvantage is no longer nearly as rewarding as it once was.

Even being a base Plat for those years was very, very good. The people at MCI were very friendly and the people at ORD weren't bad either. All of that has completely changed.

Had a 2-year project in Denver and then a year and a half in Seattle. That turned into a 3-year run of UA 1P and eventually a year of 1K. The SWUs were still pretty usable on TATL although useless on TPAC. That was okay, but honestly I don't think it was as good as being AA Plat in the 90s.

I gamed A3 for a couple years of Star Gold. Now I'm accruing at AS but don't expect their program to stay as good as it is for more than another year or so. Once they fully digest their merger, I'm sure they'll gut their FFP because that's what everybody else has done.

To this day I've been a minimal participant in Skyteam. I was DL Silver once because our corp TA gave it to me (unsolicited) as part of some promotion to get us to fly Delta. But I had no need for Atlanta or Salt Lake City, so it was mostly wasted on me.

So I guess I picked an FFP because it didn't make me wake up as early as its competitor.