All just my personal opinion
Beethoven: Piano Sonata No.15 in D major, op.28, “Pastoral” — comparing recordings with the following artists: Wilhelm Backhaus (1961), Paul Badura-Skoda (1969), Daniel Barenboim (1984), Ronald Brautigam (2005), Emil Gilels (1982), Friedrich Gulda (1967), Artur Schnabel (1935)
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)
Lieder recordings (Beethoven & Schumann) with Fischer-Dieskau/Moore, Wunderlich/Giesen, Goerne/Schneider, Terfel/Martineau, Bostridge/Drake; Schumann: Piano Quintet op.44, Piano Quartet op.47 — Melnikov/Jerusalem Quartet, Levine/LaSalle Quartet; Webern: 6 Bagatellen, 5 Movements for string quartet, op.5 — Hagen Quartett