I'm a UA Silver who lives near EWR so they're normally the go to choice if prices are right.
I started a Delta status challenge recently and flew two flights (4 segments) so far.
I really like the product over UA and AA. In this environment a comfort + upgrade is highly attainable. Nice to have a few free beers in the cabin and having access to Delta lounges with the Amex Plat card is a plus. I've been upgraded to first on 1 of 4 segments which I know is not the norm.
I like that DL doesn't let biz/first seats fly out empty. I don't care for AA's "500 mile stickers" system anymore.
With the status accelerator it'll only take $500 in spend to keep status for 2022.
FYI, Delta having free live TV in the backseat entertainment system is great especially if you're into sports.