I also started exploring Mahler with Eliahu Inbal... his reading of the 4th as well as Simon Rattle's take on the reconstruction of the 10th and Bruno Walter/Kathleen Ferrier great Songs of the Earth.
Thanks to Tim and Kal I now also have the Fischer 2,4,6, Tilson Thomas 1 and 5 and Bernstein's 5 and also picked up an Alan Gilbert's 9 on my own. Can only confirm everyone's suggestions above. Fantastic.
I am considering this...the Bruno Walter Sony Master Series set includes two versions of the Titan, one with the New York Phil and also the one with the Columbia... I like Bruno Walter with Bruckner and Mozart... any thoughts on his Mahler Symphonies?
Graham