If you are confident the destinations you listed are all that you need then you'll be fine. You didn't mention where your international trips typically are.

I was 1K at United at SFO and got tired of the lack of upgrades, surly dragon CSRs, and bitter FAs (altho they gotten a ton of new hires in recent years so this may have improved). Alaska is consistently better in these regards (not perfect, but a rude FA is pretty rare and reservations is always courteous for MVPs and not outsourced overseas).

I do miss UAs network for nonstops. Oneworld airlines are great onboard, but finding a low fare on these flag carriers is sometimes diffiicult, and often at ends with United's nonstops. But the onboard product in Y often beats UA (CX A350 Y class is terrific compared to UA). BA's PY is quite nice, and Latam's J class in both versions was quite good and with excellent service. They have access to SQ as well.

I also find Alaska has a lot of ticketing issues on international partner airlines where as United was more likely to offer flights on their own metal (thus fewer ticketing variables).

AA often is the only option for other cities which also usually means a connection (and many of them have been super short for cnxn from/to SFO which is just begging for a rebooked middle seat), but that could change on AA or UA for that matter. Earning on all partners is a percentage of miles flown...often just 25% on AA lower Main fares.

I have been very happy with Mileage Plan as well as upgrades as a MVP Gold in SFO. Just wish the network was better and less issues with partner tickets.