I fly both exclusively in paid F and do prefer Delta's FAs, although on recent flights I've had a good experience with AA's FAs. Also, Delta serves a far better IPA (Sweetwater) compared to AA's lousy Goose Island. I usually order a special meal of one type or another and prefer AA's. On the other hand, I haven't found enough of an overall difference between the two carriers to warrant going beyond what would be the best flight itinerary for me on any given day.