I never said DL sucked. Their domestic 763s are just not nice. Or at least the one I was on. The interior was very old and the legroom was near to nothing. I just think AA's onboard-service (as a comparison) is better.
That was not my only bad DL experience. Back in the day, when SR and DL were partners I flew them quite often. I also had bad experiences on a ATL-ZRH leg (int'l 763) and LAX-OGG-LAX (L1011), among others.
The service on Delta is (or at least was, I am referring to my flights over 1.5 years ago - they might have improved) nowhere near to the standards of other airlines like BA, SR or LH.
Don't get me wrong, I am not con-Delta. My experiences with them just weren't good enough to call them great. This is my personal opinion, others might think they're great - that just doesn't mean I have to as well.
Maybe the time will come and I'll give them a try again. Who knows, rumor has it that LX(ex-SR) could join SkyTeam.