TATL economy does not vary a whole lot, except for Virgin Atlantic. Check seat size and pitch, and avoid the A380 (just too many people in econ). Food varies widely, though. I prefer AF economy on food. I have not had bad service on AF. (I've had unpleasant economy experiences due to other flyers, though, such as drunk/odiferous seatmates, and people not wanting me to recline on overnight flights. One of the main reasons I work desperately to get upgrades.)