check those other threads, but in economy I really don't think it will make much difference - the A340 is a nice quiet aircraft (relative to, say, a 777 you might fly on BA to EWR) and has the advantage of a 2-seat block by the window (whereas the BA planes on a 777 would be 3-3-3 or 3-4-3 (can't remember where we are with densification these days...)

it will be BA catering either way

probably just stick with the flight if the timing is convenient for you