All just my personal opinion
Mozart: Rondo in A for Piano & Orchestra, K.386 — Clara Haskil, Bernhard Paumgartner, Wiener Symphoniker / Vladimir Ashkenazy, István Kertesz, London Symphony Orchestra / Kristian Bezuidenhout, Petra Müllejans, Freiburger Barockorchester
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
Beethoven, Piano Sonata No.8 in C minor, op.13, “Pathétique” — Backhaus (1958), Barenboim (1984), Badura-Skoda (1969), Schnabel (1935), Fischer (1952), Gulda (1967), Immerseel (1983), fortepiano), Gilels (1980), Brautigam (2003, fortepiano); Piano Sonata No.14 in C♯ minor, op.27/2 — Badura-Skoda (1969), Barenboim (1984), Backhaus (1958), Gulda (1967), Schnabel (1935), Pletnev (1988), Gilels (1980), Immerseel (1983), fortepiano), Brautigam (2003, fortepiano)
Beethoven, 12 Variations on “Das Waldmädchen”, WoO 71 — comparing recordings with the following artists: Emil Gilels (1968), Vladimir Ashkenazy (2006), Olli Mustonen (1993), Ronald Brautigam (2010)
Beethoven: Violin Sonatas — Summary for comparisons of recordings, involving the artists Busch/Serkin, Capuçon/Braley, Faust/Melnikov, Grumiaux/Haskil, Kremer/Argerich, Menuhin/Kempff, Mullova/Bezuidenhout, Oistrakh/Oborin, Perlman/Argerich, Perlman/Ashkenazy, Szeryng/Rubinstein
Beethoven: Sonata for Piano and Violin No.3 in E♭ major op.12/3 — comparing 9 recordings: Busch/Serkin (1933), Capuçon/Braley (2009), Faust/Melnikov (2008), Grumiaux/Haskil (1956), Kremer/Argerich (1985), Menuhin/Kempff (1970), Mullova/Bezuidenhout (2010), Oistrakh/Oborin (1962), Perlman/Ashkenazy (1974)