OK, so the natural "progression" (backwards) from Mahler is to Bruckner. Over the years, here's what I've acquired based on a whole variety of recommendations.
#0: Chailly, RSO Berlin
#1: Sawallisch, Bayerisches Staatsorchester
#2: Solti, Chicago SO
#3 [first version]: Inbal, Radio-Sinfonie-Orchester Frankfurt
#4: Jochum, Berlin PO
#5: Haitink, Vienna PO
#6: Klemperer, New Philharmonia O
#7: Inbal, R-S-0 F
#8: Chailly, RSO Berlin; Haitink, Concertgebouw; Ballot, Oberosterreichisches Jugendsinfornieorchester
#9: Walter, Columbia SO; Giulini, Vienna PO; [completed version] Schaller, Philharmonie Festiva
Number of CDs clearly reflects preferences among the ten.
I've heard Celibidache in concert, and am surprised to find I don't have any recordings of his. What the "best" interpretation of any of these that I'm missing?