All just my personal opinion
Schumann: Liederkreis op.39, Dichterliebe op.48 — comparing recordings with the following artists: Fischer-Dieskau/Moore (Live, 1956), Fischer-Dieskau/Brendel (1986), Goerne/Schneider (1998), Terfel/Martineau (1999), Wunderlich/Giesen (1965), Bostridge/Drake (1997); notes about related recordings
Bach: The Motets — comparing recordings with the following artists: Bernius (2012), Christophers (1989), Gardiner (1980), Gardiner (2011), Harnoncourt (1980), Herreweghe (1985), Junghänel (1995), Katschner (2012)
Beethoven: String Quartet op.131 — comparing recordings with the following ensembles: Alban Berg Quartett (1984), Amadeus Quartet (1963), Artemis Quartet (2002), Brooklyn Rider (2011), Busch Quartet (1936), Emerson String Quartet (1997), Endellion String Quartet (2005), Guarneri String Quartet (1969), Hagen Quartett (1999), LaSalle Quartet (1977), Leipziger Streichquartett (1994), Melos Quartett (1985), Quartetto Italiano (1969), Takács Quartet (2004)
Beethoven: String Quartet op.130 — comparing recordings with the following ensembles: Alban Berg Quartett (1983), Amadeus Quartet (1962), Artemis Quartet (2009), Busch Quartet (1941), Emerson String Quartet (1997), Endellion String Quartet (2006), Guarneri String Quartet (1969), Hagen Quartett (2001), LaSalle Quartet (1972), Leipziger Streichquartett (2006), Melos Quartett (1985), Quartetto Italiano (1969), Takács Quartet (2004)
Beethoven: String Quartet op.127 — comparing recordings with the following ensembles: Alban Berg Quartett (1982), Amadeus Quartet (1963), Artemis Quartet (2010), Busch Quartet (1936), Emerson String Quartet (1997), Endellion String Quartet (2008), Guarneri String Quartet (1969), Hagen Quartett (2004), LaSalle Quartet (1976), Leipziger Streichquartett (2001), Melos Quartett (1984), Quartetto Italiano (1968), Takács Quartet (2004)
Beethoven: String Quartet op.95 — comparing recordings with the following ensembles: Amadeus Quartet (1960), Artemis Quartet (2005), Busch Quartet (1932), Chiaroscuro Quartet (2012), Emerson String Quartet (1997), Endellion String Quartet (2008), Guarneri String Quartet (1968), Melos Quartett (1984), Quartetto Italiano (1971), Takács Quartet (2004)