For me it's not (in my experience) the debatable customer service, in London, on board or elsewhere, very average lounges, usually dirty planes or outdated seating in J.

What I like best about BA, and is one of the primary reasons in choosing any carrier I fly, is the impression I have (rightly or not) of well trained pilots and cabin crew, and well executed maintenance. I have confidence that the metal tube won't fall out of the sky, and if it does go wrong there will be a couple of capable pilots up front. I have QF on that same list, and CX too, for the same primary reasons.