All just my personal opinion
Robert Schumann’s Cello Concerto in A minor, op.129, in the new recording with Jean-Guihen Queyras and the Freiburg Baroque Orchestra, directed by Pablo Heras-Casado, compared to legacy recordings with Gregor Piatigorsky & Sir John Babirolli / London Philharmonic Orchestra (1934) and Mstislav Rostropovich & Gennadi Rozhdestvensky / Leningrad Philharmonic Orchestra (1961)
Robert Schumann’s Violin Concerto in D minor (WoO 1 [H/K WoO 23]), in the new recording with Isabelle Faust and the Freiburg Baroque Orchestra, directed by Pablo Heras-Casado, compared to a recording with Christian Tetzlaff and Paavo Järvi / RSO Frankfurt
Franz Schubert’s Four Impromptus op.90 (D.899), in interpretations by Arthur Rubinstein (1928, 1949, 1950, 1958, 1961) and András Schiff (1990)
Felix Mendelssohn Bartholdy: Songs without Words (Lieder ohne Worte) played by Ilse von Alpenheim, in her complete recording from 1980 — there’s more to this than mere encores! Also included are two interesting sets of variations (opp.82 & 83), and the Andante cantabile e presto agitato in B major
Johannes Brahms, Violin Sonata No.2 in A major, op.100, in 3 interpretations: Henryk Szeryng & Arthur Rubinstein (1960) / Leonidas Kavakos & Yuja Wang (2013) / Isabelle Faust & Alexander Melnikov (2015)
Richard Strauss, Violin Sonata in E♭ major, op.18 in three interpretations: Haifetz / Sándor (1934); Spivakov / Bezrodnyi (2001); Frang/Lifits (2010) — and memories only (sadly) of an LP recording with Ulf Hoelscher and Michel Béroff (1978)