Perhaps the most widely admired living Mahler conductor among professional musicians right now is Claudio Abbado. Though some of his recordings do not have the best sonics, they are all well worth listening to.
CSO Resound - Mahler 1 SACD
I encourage you to pick up a copy of this recording of Mahler's 1st symphony, performed by the Chicago Symphony Orchestra. Recorded in May of 2008 for the CSO's label CSO Resound. Conducted by Bernard Haitink. Issued on CD and SACD. Whether or not you like the performance is up to you, but the sonics on this one are amazing. Check it out.