All just my personal opinion
Concert review, ★★★★½, Esther Hoppe, Veronika Hagen, Clemens Hagen / Festival Sommerklänge @ Aegerihalle, Unterägeri, 2021-07-18 — Beethoven: Serenade for Violin, Viola, and Cello in D major, op.8; Mozart: Divertimento in E♭ major, K.563
Blog post #582 — #rolfsmblog •
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: Adagio & Fugue in C minor, K.546 — Hagen Quartett / Chiaroscuro Quartet;
Mozart: 6 Variations for Piano & Violin on “Au bord d’une fontaine” in G minor, K.360/374b — David Oistrakh, Paul Badura-Skoda / Petra Müllejans, Kristian Bezuidenhout
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: 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)