I will add another vote in favor of the Payare/OSM M5 (I have no opinion of the Bychkov as I do not own it). After listening to the short excerpts and liking what I heard, I decided to get a copy of the CD. I recently listened to it on a long drive in my car and was delighted with the counterpoint, audible inner voices, integrated coherence of the ensemble, and the overall performance start to finish. While I admire virtuoso instrumentalists (I appreciate other M5s on disk for that), this one really shows that Mahler had ensemble in mind not just tuneful highlights strung together. I heard the English horn like never before. The string playing was not just an aural smear in the vigorous sections. The Adagietto was faster than many but neither trivial nor insensitive. The timings are similar to Bertini, Saraste, and Abbado, all performance I also favor.