Not really my experience,as far as BA/AF are concerned. Different styles, certainly, but not necessarily better or worse. BA crew tends to do more cabin rounds but AF tends to be somewhat better at anticipating requests, IME. BA crew would be somewhat more familar (which would be perceived by the English as friendlier) whereas AF crew tend to be somewhat more formal, as befits French social norms (but not in an Asian style). I don't fly Swiss enough to have a clear impression of LX crews.