I would agree ... for the moment I think United is winning.
Flew Singapore Airlines earlier this year from San Fran to Singapore ... 14 hour flight in business class and a very pleasant experience as far as flights of that duration go. Returned on United to San Fran from Hong Kong, a flight of approx. 11 hours ... on a upgraded coach class ticket ... very unpleasant experience. Went United on that portion of the trip because it was homeward bound and I used my United Skymiles.
Sing air is great
I have flown Singapore multiple times between the US and Asia ( KrisFlyer member). It’s a top notch airline. Cathay is nice too. Makes me hate flying US airlines.