My husband reacts the same way:
- On KLM he eats and drinks in the lounge, sits in his extra legroom seat, and thinks KLM is great.
- On DL he also eats and drinks in the lounge (technically due to AMEX) and sits in his extra legroom seat, but just because he see's his name always on the upgrade list but almost never making it he thinks Delta is useless.

It certainly isn't rational, but that's life!