By the way, on a semi-related note, for Bach's Die Kunst der Fuge, I'll give a big for the Keller Quartett's (fairly) recent recording on ECM New Series. When you hear the Keller play it, and then listen, say, to the Emerson Quartet, it's almost as if you're hearing different compositions, or an altogether different period of music. I like the Emerson Quartet, but (to my not-so-sophisticated classical ears) they seem to "Mozart-ize" the fugues.
Another rec on ECM New Series (Bach-related): Till Fellner's recording of The Well-Tempered Clavier is pretty good. Maybe too much of a polished edge at times, but still luscious.
I don't really care for "jazz" on ECM, but I think the way Manfred Eicher records classical music is beautiful.