And the FAs on UA can be pretty bad.

I've noted this elsewhere, but I've always thought that DL's main advantage were its people, especially in flight. Over the past year or two, I've noticed this slipping. It used to be that DL FAs were consistently good so that a bad one was noticeable. In my opinion, it's starting to be more generally hit or miss. This was my experience at UA, which was so unpredictable that I would no longer pay to fly in their premium cabins. To me, DL is starting to lose this advantage.