All just my personal opinion
Der Ring des Nibelungen, part 4 — comparing 2 recordings: Furtwängler (1953, Rome), with Suthaus, Mödl, Greindl, Poell, Jurinac, Klose, Pernerstorfer, etc.; Janowski (1980), with Kollo, Altmeyer, Salminen, Nöcken, Sharp, Wenkel, Nimsgern, 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