My top Tristans are:
1. 1936 - Reiner - Melchior, Flagstad, Kalter, Janssen - London
2. 1952 - Furtwängler - Suthaus, Flagstad, Fischer-Dieskau - London
3. 1952 - Karajan - Vinay, Mödl, Malaniuk, Hotter - Bayreuth
4. 1966 - Böhm - Windgassen, Nilsson, Ludwig, Wächter - Bayreuth
5. 1980-82 - C. Kleiber - Kollo, Price, Fassbaender, Fischer-Dieskau - Dresden
The Reiner has Melchior and Flagstad in their prime. They are probably the most famous pair of lovers. The Furtwangler is the classic recording. It has a strong cast, is a studio recording, and has great conducting. Furtwangler was a master at Wagner. Karajan's Tristan is also first rate. Vinay is a dark-toned Tristan (baritonal) and modl brings a mezzo quality to the role. The supporting cast is better than the Furtwangler. The 1966 Bohm is the reference recording of this opera. An excellent choice. All roles are well cast. Incredible live performance. Lastly, the Klieber has one of my favorite Isoldes in Margaret Price, very feminne. Kollo is very good, although somewhat past his prime. The support is great. Amazing conducting as well.