The Times ran a taste-test on a limited number of carriers’ longhaul offerings a little while ago:
and no-one could forget the famous Virgin letter:
With reference to The Times’ findings, I’ve sampled both BA and CX Economy recently, and I’d tend to agree with what they thought in 2009:
Overall though, I’m tending more and more towards taking my own food, completely or supplementarily on more and more flights these days, especially in Economy. Ultimately, the quality can be as high as you like, but if quantity is lacking then that’s potentially a greater issue for me.