OK, Bach's a good choice for #1, but any list without Duke Ellington is pointless. "Oh, but it's supposed to be 'classical' composers." Please - Ellington is stylistically closer to Bach then a lot of Bartok or any late Stravinsky (or early, for that matter). He was America's greatest composer and belongs somewhere on here.
Mozart and Beethoven are no-brainers. Schubert leaves me cold - sorry. Most opera after Mozart and before Glass is also lost on me, but I freely admit that's a personal preference and more an indication of my lack of sophistication about these things than anything. But I'd have Haydn on any list before Verdi even if I loved opera.
Debussy - sure, but not before Stravinsky, the best orchestrator and formal thinker of the past century. I like Brahms, but Chopin created these beautiful little worlds, as did Webern.
So, for me:
- Ellington (close...)
- Tchaikovsky (Seriously? Yeah, maybe...)