All just my personal opinion
Bach, St.John Passion BWV 245, with the following artists: Harnoncourt / Equiluz (1965), Jochum / Haefliger (1967), Rotzsch / Schreier (1976), Koopman / de Mey (1993), Suzuki / Türk (1998), Gardiner / Padmore (2003), Layton / Bostridge (2012)
Der Ring des Nibelungen, part 3 — comparing 2 recordings: Furtwängler (1953, Rome), with Suthaus, Patzak, Frantz, Greindl, Klose, Streich, Mödl, etc.; Janowski (1980), with Kollo, Schreier, Adam, Nimsgern, Salminen, Wenkel, Sharp, Altmeyer etc.
Der Ring des Nibelungen, part 2 — comparing 2 recordings: Furtwängler (1953, Rome), with Frantz, Mödl, Windgassen, Frick, Konetzni, etc.; Janowski (1980), with Adam, Minton, Altmeyer, Jerusalem, Norman, Moll, etc.
Der Ring des Nibelungen, part 1 — comparing 2 recordings: Furtwängler (1953, Rome), with Frantz, Windgassen, Neidlinger, Patzak, Grümmer, Greindl, Frick, etc.; Janowski (1980), with Adam, Minton, Schreier, Nimsgern, Wenkel, Salminen, Popp, Schwarz