All just my personal opinion
Beethoven: 6 Bagatelles, op.126 — Ashkenazy (1984), Brautigam (2010), Brendel (1964 & 1985), Gould (1974), Schnabel (1937); Beethoven: 24 Variations on the Arietta “Venni Amore” by Vincenzo Righini, WoO 65 — Pletnev (1997), Brautigam (2012); Schubert: Symphony in B minor, D.759 (“Unfinished”) / Symphony in C major, D.944 (“Great C major”) — Furtwängler (1952), Harnoncourt (1992), Dausgaard (2006)
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)