For me, the award has to go to Thai: the hard product was fine (although not outstanding), but I had a terrible experience with every TG employee I encountered start to finish on the journey. I also think BKK is a terrible transit hub - only place I've ever seen a sign indicating I needed to walk more than a kilometer (!), and the lounges were dank, depressing caves with mediocre food options.
Maybe I'd have had a better experience if I was flying F rather than J, of course. But I'd heard people rave about their service on FT, and I can't see how they're possibly in the same league as any top tier Asian carrier.