All just my personal opinion
Concert review, Hagen Quartett @ Stein am Rhein, 2017-10-01 — J.S. Bach: “The Art of the Fugue”, BWV 1080 (Contrapunctus I, II, III,IV); D. Shostakovich: String Quartet No.15 in E♭minor, op.144; F. Schubert: String Quartet No.14 in D minor, D.810, “Death and the Maiden”
Mozart: String Quartet K.428 — comparing recordings with the following artists: Alban Berg Quartett (1990), Chiaroscuro Quartet (2012), Hagen Quartett (2001), Hagen Quartett (2010), Quartetto Italiano (1966)
Beethoven: Great Fugue op.133 — comparing recordings with the following ensembles: Alban Berg Quartett (1983), Amadeus Quartet (1962), Artemis Quartet (2011), Busch Chamber Players (1941), Emerson String Quartet (1997), Endellion String Quartet (2006), Guarneri String Quartet (1969), Hagen Quartett (2001), LaSalle Quartet (1972), Leipziger Streichquartett (2006), Melos Quartett (1984), Otto Klemperer/Philharmonia Orchestra (1956), Quartetto Italiano (1969), Quatuor Mosaïques (2016), Takács Quartet (2004)
Beethoven: String Quartet op.132 — comparing recordings with the following ensembles: Alban Berg Quartett (1984), Amadeus Quartet (1962), Artemis Quartet (1998), Busch Quartet (1937), Emerson String Quartet (1997), Endellion String Quartet (2005), Guarneri String Quartet (1969), Hagen Quartett (2003), LaSalle Quartet (1973), Leipziger Streichquartett (2001), Melos Quartett (1985), Quartetto Italiano (1967), 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)