I've flown United, BA, and Air France and out of the three, AF was the worst (funny, they've also merged in with Delta I think).
United I flew business class, so I've got absolutely no complaints there. Food was great, complimentary stuff was great, staff was wonderful. BA was in economy and fine, and I appreciated the little kit with socks, a toothbrush, etc. Air France? Nothing. You get an eyemask and earplugs. No socks, no complimentary toothbrush, just an eyemask and earplugs. The food wasn't the greatest, either. They passed out menu's and there was a fish dish, so mom was going to get the fish...and we just got handed the pasta dish without being asked what we wanted! They never came around with extra water, and when I rang my bell to ask for some, I got told it was self serve and I shouldn't bother them! Sorry, but no one told me it was self serve! It was just horrible and I'm never flying AF again.