I too think AS might be a good choice, especially if you're from SEA:
https://onemileatatime.com/alaska-mi...tatus-changes/
https://onemileatatime.com/qatar-airways-seattle/
AS is one of very few (the only?) programs where you earn bonus award miles based on your status, even when you're flying with partners.
So you can buy a cheap QR business class R fare ticket and earn up to 350%.
The only thing I'm not so sure about is lounge access for domestic US flights. I know that AA elites often don't get access, while e.g. BA elites do get in.
Not sure how this would be handled with AS.