Ok, here's my preliminary list for a desert island collection, with max 3 in each category (works joined by 'or' I haven't decided on yet):
Piano concertos: Beethoven 4, Brahms 1, 3rd place would be a painful choice between Beet. 5, Brahms 2, or one of Mozart 20,21,22,23,24,25
Non-piano Concertos: Beethoven & Brahms violin, Mozart Clarinet
Fave concerto overall: Beethoven either 4th or violin
Symphony: Beet 3, 7 or 9; Brahms 1 or 4; Mozart 40 (Am I allowed to replace the last two movements of 40 with the last two of Beethoven 5, maybe transposed? I know this ruins the overall structure, but I can't live without the outer movements of this hybrid symphony.)
Piano sonata: Liszt Bminor; Beet op 106; Schubert Bb or Beet 111
Long piano piece other than sonata: Chopin Barcorolle, ballade 4; Liszt Benediction de Dieu or Vallee d'Obermann
Suite of piano pieces: Schumann Carnival, Chop op 10, Liszt transcendental etudes
Piano/keyboard variations: Schumann Symphonic variations, and 2 of: Beet Diabelli, Brahms Paganini, Bach Goldberg
Choral: Mozart Requiem, Brahms Deutsches Requiem, Bach B-minor mass
Opera: Mozart Don Giovani
Overture: Beethoven Egmont, Leonore 3
Rock albums: Beatles Abbey Rd, Rolling Stones Let it bleed, Led Zep IV or Physical Graffiti (4th: Nine Inch Nails: The Fragile)
Rock songs: Led Zep. Stairway to Heaven, Queen Bohemian Rhapsody, Beatles A day in the life or Led Zep: In my time of dying.