As a DL PM and a recently minted AA Plat I've spent some time in both FC on MD80s for both airlines ...

AA food can be better but it can be worse (as I found out with a Denver Omlet like thing a few weeks ago) ...

The service for me on DL has been much better than on AA with regards to how the FAs have treated me ... granted I am only 27 and look at least 5 years younger than that but the FAs on DL have treated me like a FC passenger whereas the AA FAs have treated me like I was just lucky to be in FC on the AA flights ...

YMMV but I personally would choose DL over AA for FC flights