Since I've just surveyed the M8s I have on hand, a brief summary:
Rattle, Boulez, Sinopoli and Abbado/Berlin all struck me as having cast, SQ problems or both.They're at risk of donation to open up some shelf space.
Chailly is very well recorded, but Ben Heppner sounds thinner than on the fine Colin Davis/BSRO recording, and he's not the only problem with the cast.
Recordings in my top rank: Ozawa is very fine, with Gwynne Howell outstanding as Pater Profundus. Peter Lika also sings a fine PP for Gielen, overall a distinguished performance. Shaw/Atlanta is more than respectable, kind of a sleeper. Zinman and Inbal/Frankfurt are very fine. I remember liking Tennstedt, but this is really an outstanding recording in every way, including a fine cast, far better than usual SQ from EMI, a particularly enthusiastic children's choir, and intense engagement from the podium, start to finish.
Haitink is indeed very good, with somewhat dated SQ (redbook). I didn't get around to Kubelik this time around, but he deserves his legendary status.
That's not every recording I listened to this time around, but there you have it.