All just my personal opinion
Beethoven: Sonata for Piano and Violin No.9 in A major, op.47, “Kreutzer Sonata” — comparing 12 recordings: Busch/Serkin (1941), Capuçon/Braley (2009), Faust/Melnikov (2008), Grumiaux/Haskil (1957), Kremer/Argerich (1995), Menuhin/Kempff (1970), Mullova/Bezuidenhout (2009), Oistrakh/Oborin (1962), Perlman/Ashkenazy (1975), Perlman/Argerich (1998), Szeryng/Rubinstein (1958), Tur Bonet/Vişovan (2020)
Beethoven: Sonata for Piano and Violin No.10 in G major, op.96, “The Cockcrow” — comparing 8 recordings: Capuçon/Braley (2009), Faust/Melnikov (2008), Grumiaux/Haskil (1957), Kremer/Argerich (1995), Menuhin/Kempff (1970), Oistrakh/Oborin (1962), Perlman/Ashkenazy (1975), Tur Bonet/Vişovan (2020)
Beethoven: Piano Sonata No.26 in E♭ major, op.81a, “Les Adieux” — comparing recordings with the following artists: Wilhelm Backhaus (1961), Paul Badura-Skoda (1969), Daniel Barenboim (1984), Ronald Brautigam (2007), Emil Gilels (1984), Friedrich Gulda (1967), Arthur Rubinstein (1940 and 1962), Artur Schnabel (1935)
Beethoven: Piano Sonatas — summary for comparisons of recordings, involving the following artists: Wilhelm Backhaus, Paul Badura-Skoda, Daniel Barenboim, Ronald Brautigam, Edwin Fischer, Emil Gilels, Friedrich Gulda, Clara Haskil, Jos van Immerseel, Julius Katchen, Wilhelm Kempff, Igor Levit, Mikhail Pletnev, Maurizio Pollini, Svjatoslav Richter, Arthur Rubinstein, András Schiff, Artur Schnabel, Mélodie Zhao
Comparing recordings with the following artists: Müllejans/Bezuidenhout (2008), Tetzlaff/Vogt (2011), Oistrakh/Badura-Skoda (1972), Grumiaux/Haskil (1956)
Chopin: Piano Concerto F minor, op.21 — comparing recordings with the following artists: Askenase/Ludwig (1963), Avdeeva/Brüggen (2012), Haskil/Markevich (1960), Rubinstein/Barbirolli (1931), Rubinstein/Steinberg (1946), Rubinstein/Wallenstein (1958), Rubinstein/Ormandy (1968)