Don't get me started on United. I refuse to fly with them (LHR to SFO about 4 times a year) for a myriad of reasons, not limited to: food quality, delays, total failure of in-flight entertainment system and taking an extra 1.5 days to get me home (direct flight cancelled, so shunted via Dulles). I'm a tolerant person, but United excelled at pissing me off.