All just my personal opinion
Beethoven: String Quartets — summary for comparisons of recordings, involving the following ensembles: Alban Berg Quartet, Amadeus Quartet, Artemis Quartet, Brooklyn Rider, Busch Quartett, Chiaroscuso Quartet, Emerson String Quartet, Endellion String Quartet, Guarneri String Quartet, Hagen Quartett, Kuijken Quartet, LaSalle Quartet, Leipziger Streichquartett, Melos Quartett Stuttgart, Quartetto Italiano, Quatuor Mosaïques, Takács Quartet
Beethoven: String Quartet op.135 —comparing recordings with the following ensembles: Alban Berg Quartett (1982), Amadeus Quartet (1963), Artemis Quartet (2011), Busch Quartet (1935), Emerson String Quartet (1997), Endellion String Quartet (2005), Guarneri String Quartet (1969), Hagen Quartett (1990), Hagen Quartett (2012), LaSalle Quartet (1976), Leipziger Streichquartett (1998), Melos Quartett (1984), Quartetto Italiano (1968), Takács Quartet (2004)
Beethoven: String Quintet op.29 — comparing recordings with the following ensembles: Endellion String Quartet & David Adams (2008), Kuijken Quartet & Marleen Thiers (2006)
Beethoven: String Quartet after the Piano Sonata op.14/1 — comparing recordings with the following ensembles: Artemis Quartet (2011), Endellion String Quartet (2008), Melos Quartett (1984)
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)