Man, I just don't think it gets much better than this: Daniel Harding/Vienna Phil. doing M6. It's not clear if this is from the Lucerne Festival or the Proms in London (?).
https://www.youtube.com/watch?v=-rDUgcGhapETo me, the VPO just owns Mahler 6, and just seem to get better and better at with each passing year. They also own Bruckner 8 and the Alpine Symphony.
I like his Bavarian Radio S.O. recording of M6, although I don't think it's as well recorded. That one has an even better scherzo (but not the rest).