Scarlatti- Horowitz, Yevgeny Sudbin.
Haydn- Yevgeny Sudbin, Wilhelm Backhaus, Paderewski (for a beautiful performance of the F Minor Variations)
Mozart- Vlado Perlemuter (complete Sonatas, not well known enough this recording), Kempff (various concerti), Schnabel.
Beethoven- Solomon, Schnabel, Gilels (Piano Concerto No.4 w. Philharmonia/Ludwig), Backhaus, Cherkassky (Sonata Op.27 No.1), Horowitz (32 Vars. in C Minor), Moiseiwitsch (who should have recorded much more).
Schubert- Schnabel, Kempff, Rudolf Firkusny, Clifford Curzon.
Chopin- Cortot, Moiseiwitsch, Pouishnoff, Vlado Perlemuter, Percy Grainger (Sonata No.3, a more spontaneous and bracing performance has never been committed to disc).
Liszt- Horowitz, Louis Kentner, Georges Cziffra, Cherkassky, Emil Von Sauer, Arrau, Egon Petri.
Schumann- Cortot (esp. the 1934 Concerto w. LPO/Ronald), Moiseiwitsch (oh that there were more from him, but the Fantasie is one of the greatest of all piano recordings), Horowitz (Kreisleriana), Cherkassky.
Brahms- Solomon, Moiseiwitsch (Handel Variations), Backhaus, Clifford Curzon.
Debussy- Moiseiwitsch, Horowitz, Gieseking.
Ravel- Arthur Rubinstein, Vlado Perlemuter, Dinu Lipatti (Alborada del Grazioso).
Delius- Moiseiwitsch (Piano Concerto w. BBCSO/Sargent- no better performance exists!).
Rachmaninoff- Moura Lympany (1st Concerto w. Philharmonia/Malko), Moiseiwitsch (2nd Concerto and Paganini Rhapsody w. Philharmonia/Rignold plus any of M's other Rachmaninoff recordings), Martha Argerich (3rd Concerto w.BerlinRSO/ Chailly), Michelangeli (4th Concerto w. Philharmonia/Gracis) and of course, the composer's own recordings. Horowitz (3rd Concerto- any of 'em! and 2nd Sonata).
Well that's a rough guide- and just done quickly off the top of my head- no doubt 3 million others I should have mentioned will occur to me the minute I post this. Ne'er mind, eh??