My past and current circumstance: I have lived in the South San Francisco Bay since 1974. I bought a limited lifetime Aairpass back in 1994, shelling our $160K for 60 thousand airline miles per year, which would roll over to subsequent years if not used. I have accumulated now 740,000 miles to use, mainly by not using AA exclusively and using other carriers. I have had to use other carriers out of SFO and SJC because of reduction of service by AA. When I bought the Aairpass in 1994, AA had established a hub out of SJC.
We had fabulous service, with non stops to Honolulu (3 a day) JFK (3 a day) and even flights to Paris and Taipei, and many other destinations.

AA management gradually abandoned us in the SF Bay Area. Southwest killed the hub (at SJC anyway). AA then figured LAX would be their focus/gateway. No more service to HNL. With the pandemic, we are down to 2 non-stops daily to ORD from SFO, with one of them a red-eye and the other a 6AM departure. We generally had 6 a day. The experience of going to LAX transit hub got old very rapidly. I bought a lot of non-airpass tickets from AA and had annual spend easily near 70-80K, if one included my Aairpass allotment. I asked if they could consider me for CK, and was told (not politely) to pound sand.

So, after all these years, I plunked down $50K 2 weeks ago with UA Pass Plus. This is for a year. I already had 2.4 mm miles on UA anyway. They immediately made me GS, and I must say it is a perk that I grew to like immediately. I did the math, and although it looks I'm leaving about $40K of current airline flying/spending on the table with AA, it's like a stock I own that is underwater, but I don't take the loss because I haven't sold it yet. I can use AA as a backup if I'm tense or desperate to get somewhere. They have committed to serving the lifetime Aairpass folks like myself. I was EXP every year for all the years they had it. Now when I call the EXP line, I get the voice message that they'll call me back when it's my turn. On the weekends, that's frequently over an hour. Even during weekdays, one hour waits are frequent. So much for EXP status.

And the availability of flights on UA out of SFO is something I don't think AA can match. I wish I had bought Pass Plus before this. The deal of getting GS for $50K spend is not something that AA is guaranteeing for CK status, I think. UA has is it on the table, up front, in the contract. No guessing about whether the carrier is in the mood for high status qualification. A good point to consider if comparing. both programs.