A few I might add: Beethoven Variations in C minor, Liszt Schubert Song Transcriptions, Brahms Paganini Variations.
Where's Mendelssohn (Variations sérieuses) and Franck (Prélude, chorale et fugue)?
Where is Mozart's Fantasia in C minor and the
Sonata in C minor ?
For fun, let's see if I can do 100 without any from that original list.
BTW pay no attention to the numbers/rankings, it's mostly just the order that I happen to think of them, heavily biased by all kinds of things, including what you guys just said.
BTW #2: I agree with the surprise about Beethoven's Pastorale sonata being on such a list, even though I love the piece.
1. Beethoven Variations in C minor
2. Schubert-Liszt Widmung
3. Mendelssohn Variations sérieuses
4. Franck Prélude, Chorale and Fugue
5. Mozart Fantasia in C minor
6. Mozart Sonata in C minor
7. Brahms Variations on an Original Theme, Op. 21 #1
8. Scriabin Sonata #10
9. Scriabin Vers la flamme
10. Chopin Ballade #2
11. Chopin Scherzo #2
12. Chopin Scherzo #3
13. Chopin Scherzo #1
14. Chopin Mazurkas Op. 30
15. Chopin Mazurkas Op. 50
16. Mozart Rondo in A minor (big omission for any such list)
17. Mozart Little Gigue in G major
18. Schumann Sonata #1 (F# minor)
19. Schumann Sonata #2 (G minor)
20. Mendelssohn Fantasy in F# minor
21. Mendelssohn Songs Without Words
22. Alkan "Concerto" (for solo piano)
23. Alkan "Symphony" (ditto)
24. Alkan Le festin d'Esope
25. Bartok Sonata
26. Bartok Mikrokosmos
27. Bartok Out of Doors Suite
28. Chabrier Pièces pittoresques
29. Beethoven Sonata Op. 78 (sometimes said to be his "favorite")
30. Beethoven Sonata Op. 7 (E-flat major)
31. Beethoven Sonata Op. 10 #3
32. Beethoven Eroica Variations
33. Clementi Sonata in F# minor
34. Schubert Sonata in A major, D. 664
35. Weber Invitation to the Dance
36. Weber Sonata #2 (A-flat major)
37. Weber Sonata #4 (E minor)
38. Debussy L'isle joyeuse (another surprising omission, perhaps an oversight)
39. Scriabin Etudes Op. 8
40. Scriabin Etudes Op. 42
The other 60 spots are easily filled by various and sundry sonatas by Haydn, Mozart, and Beethoven not mentioned yet, plus an unlimited number of pieces by Scarlatti.
BTW, I have to admit, while I'd argue for quite a few of these pieces to be among the "100," overall the original list is superior to this one.