It might be good to include the Colin Davis M8 into that mix. The men are terrific, as is the choral contribution. Ben Heppner sounds better here than he does on the Chailly M8, which I do like. While the organ is a bit undersized, the tam-tam smashes at the end of Part II are terrific. It's well worth hearing.
I like the Boulez M8 very much. It's quite unusual. Edward Seckerson (Gramophone) summed it up best, by stating that never has a performance that was so unidiomatic of Mahler, been so enjoyable to listen to. The detail is amazing, and it really doesn't bother me that Boulez's grand, over-the-top ending to Part 1 out-shines his ending to Part II (which ain't so bad, either). It could use much more audible tam-tam smashes at the end of Part II. However, the balances between the brass - both offstage and onstage - and the organ are very well gauged. I also think that the very beginning of the symphony is perfectly gauged on the Boulez - not too fast; not too slow. Not too much organ (acutally, it's hard to have too much organ); not too much brass either. Just right.
With Nagano, I like his Part I more than his Part II (a poor tenor, and way too small childrens chorus). For me, he takes way too long to get his Part II revved-up, as the Wagnerian sounding orchestral passages that happen earlier on are just too lax and calm sounding. Boulez is almost equally slow with those same passages, but there's more tension: louder horns and more rhythmic strings.
For me, Rattle is just the opposite: I like his Part II much more than his Part I. He rushes a bit in the big double fugue of Part I, as well as the ending of Part I. Some of the grandeur of that music gets robbed, not to mention choral textures not getting sufficiently clarified. But his Part II is superbly put together. Put Nagano's Part I with Rattle's Part II, and you'll have yourself one hell of a Mahler 8th.
As for the Bertini M8, I just like his pacing and priorities. I like it that he robs the "three penitant women" passages, allowing more time for the symphony's ending. Some people don't care for that, but I think that the vocal writing throughout the penitant women passages is rather over-rated. The interesting detail is in the orchestra, and it's actually easier to hear and digest at a more flowing tempo, I think.
Great piece; hard to go wrong. I probably like the Solti the least, among big-name recordings of the work. It's good if you like lots of strong brass; and loud, up-frong singers. But I think that there's a big disconnect between the strong, almost brittle sounding trumpets and trombones of the CSO, and the relatively soft voices of the Viennese choral forces. If you've ever seen a photo of how everyboy was laid out in the Sofiensaal while making that recording - well, that's just how it sounds. It was technically solid for its time. But I think it's quite dated now, especially from a purely musical standpoint.