Another PDX flier here. I was AS MVPG for years as I had clients that lined up really well with the AS network. Then a change in work trips had me shift over to DL for a few years where I was Platinum too. The pandemic also reduced the AS nonstop options for me, so for some time it was a choice of do I want to connect in SEA or ATL, and heading east, ATL was fine for me. Others have shared good points here on how much better the mileage program is on AS (I have scored JAL F via miles). Some other things I’d add:

Comparing status between two programs is tough. Platinum maps over to 75K, but I found Platinum very easy to earn compared to 75K thanks to non-flying options. On DL this meant I was in C+ all the time, but as I head back to AS I might only be in Premium Class if there is space closer to check in since I assume Gold is more realistic. Upgrades are another hard one to compare, I don’t know about you but I can count on one hand the number of FC upgrades I’ve had in the past couple years on DL. DL is selling upgrades to FC far more aggressively, AS has not gone all in on FCM like DL. For me there is a bit of a downside, on DL I can score a FC seat for 19K SkyPesos, which is fine since the miles are sort of throw away to me. But on AS I’d need to refare if I want to pay for a change from what my employer will provide.

Other items: The companion fare on AS is FAR better. It actually works so long as there are seats and you are not limited to the lower 48. But no FC companions on AS. Not a big loss to me, but some really value that. And companions on AS earn miles unlike DL.

Upgrade certificates are easier to use on DL IMO. GGUs require both space and a higher fare class to work. Can be good for close in bookings or high demand routes. But I had pretty good luck with RUCs on DL, but usually just to treat the family once a year so I wouldn’t change all my choices for that perk. And others might chime in - GGUs can be used on Companion Cert trips so it makes those higher fare class calculations “easier” to justify potentially.

Lounges on DL are some of the best, but that’s a value that varies based on how much time you want to spend in the airport in life. I will admit being able to shower and have breakfast after a 5am flight connecting in ATL or SLC is nice. But nice enough to deal with the new requirements is a whole other question. I find Alaska Lounges to be just fine for most of my uses, I am not looking for sit down dining.

Last, is price. I am increasingly seeing DL premiums on routes that have connections where AS is nonstop and $100 cheaper. I need to be mindful of costs (both time and money) so that increasingly tips the scales.

AS can have bigger meltdowns due to less back up options. I was caught in the 2021 winter storm that stranded me in Hawaii for three days. To AS’s credit they put me and my family up at the Outrigger and we just had to wait. DL has far more options to move people. But they are not immune if things get messy on the East Coast.

I find both flight crews to be diligent and kind. Bad days happen everywhere, but both phone agents and flight crews for the most part seem to be happy to help me most days.