I've been doing a long and slow 'retrospective' of Mahler 8 recordings. In the process, I've done a turnaround on the Feltz M8 - it's much better than I had previously thought. It's very well recorded and has one of the best endings to Part II ever. The Feltz is one of three M8 recordings in which the conductor has his unified choruses hang on to the very last syllable they sing in the entire symphony ("hiiiiiiiiiii,naaaaaaaaaaaaaaaan") - the other two being the Colin Davis and the JoAnn Faletta ones (both conductors I like very much, in general). While Feltz uses much smaller adult choral forces than usual - just a little over 100 singers each in Chorus I and Chorus II - his children's choir has over 40 members. Thus, he has a higher than normal ratio of children to adults. Remember, Mahler had well over 300 children when he premiered the work in Munich in 1910. I wouldn't go so far as to call the Feltz 'the best', but it's really quite good - better than I had first thought.
I'm sorry to say that I just can't get over the faults of the Jurowski/L.P.O. M8 - namely the quality of the captured sound itself. Vocal soloists tend to be a bit too far forward. There are other small annoyances too. That's too bad, because there really is some terrific playing and choral singing in it. I think the recording would have been more 'flattering' to the vocal soloists, if they had simply been placed farther back in the perspective.
A big 'sleeper' for me is the JoAnn Falletta M8, which was performed and recorded in Virginia. It's not the best recorded, but it's a really nice performance.