I know DL has a great reputation, and I love them too, but the last year has not been good IMHO.
UA has gotten things shockingly right for the last year. Competent ops all around, great IT, best website and app that actually work, call center you can actually get through to with ease, onboard service has been at the front side the pack (alcohol in F, beverages in Y, F meals coming back, etc,). UA’s main fail has been in getting clubs back open. DL has absolutely excelled there, but has been woefully behind UA on all the other attributes I just cited.
I’m GS & DIA, so I get to see both sides. I personally think UA doesn’t get enough credit for how it has handled the last year, and for the overall good operation they run.