Since we seem to be talking about modern recordings, I would suggest Abaddo and MTT in M3.
Which Abbado? Lucerne, Vienna or Berlin? Honestly, I've not listened to MTT in quite awhile. I will revisit it in the very near future.
For older recording I really love Horenstein. That's almost a given, though. Kondrashin has always had a place in my heart with the Mahler 3, too. I have a thing for all of Kondrashins Mahler.