Out of those I have flown, SQ definitely. They have definitely captured the right atmosphere. I haven't flown on Lufthansa, but from the photos, it looks to bionic and sterile, and not homely enough. Same for UA and BA. I have flown MH as well, and I thought theirs was almost as good as SQs, but not quite (although it was my first flight on a 777). Looking at pictures, I'd have to say that VS's is also really nice (but, despite my name, i have yet to set out and fly them, I was meant to be in 2 weeks time, but, alas, travel plans changed...).
"So powerful is the light of unity that it can illuminate the whole earth." - Bahá'u'lláh