Welcome to FT,

It all depends from which airport you fly: I usually do from ATL and on that route I prefer AF as they fly with 777 which I prefer to 767's although DL has on some flights 777 as well.
From the US to CDG, the food is approximately the same, I do believe AF has a better Economy. As for the service it is a lottery from flight to flight. They maybe extremely friendly and the next flight the contrary. I must add I have no experience in coach, but from what I have seen, AF seemed better.

In ATL all international flights leave from Concourse E, so it makes no difference for boarding. Often is AF closer to the restaurants than DL. Boarding procedure is the same.

I said welcome to FT because I read 12 posts instead of 126, sorry, you are an older member than I...