I started with Pan Am and TWA because I like to go to Europe as often as possible. Then Pan Am went away, and TWA sold its JFK-London route. I switched to BA (this was before the rise of alliances) because there are few places one cannot get to on BA. I have rarely had a problem getting an award seat on BA out of EWR for the exact day I wanted, so I've pretty much stuck with BA. I've added CO because, well, I fly out of EWR...