I'd sooner die than call classical the best non-metal music. Worst is more like it. Just because it's fancy and high class, people don't have the nerve to call it shit. It's just another music style like all the others, it should get no more or less respect. I don't mind people loving it and respecting it, but I'm going to put my 2 cents in about it too. Classical is interesting from an intstrumental standpoint but it's the most faceless and mindless of music styles.
Eh, anyway, my picks for best non-metal albums would be...
1. Pink Floyd - The Final Cut
2. Nirvana - With The Lights Out
3. Bob Dylan - s/t
4. Led Zeppelin - s/t
5. Neil Young - Time Fades Away
6. Tom Petty & The Heartbreakers - Echo
7. The Doors - LA Woman
8. Neutral Milk Hotel - In The Aeroplane Over The Sea
9. Jeff Buckley - Live at Sin-e'
10. Alice In Chains - Dirt
Yes I included some compilations on there, but to me the best is the best. I think you can put together a compi to sometimes work better than the original albums did. I could have easily gone with 4 or 5 albums from the best artists but it's a lot more interesting if I restrict it to one album per artist. (Honorable mentions: Regina Spektor - Begin To Hope, Jimi Hendrix Experience - Axis Bold As Love, Jake Holmes - The Above Ground Sound Of, Robert Johnson - Complete Recordings, King Crimson - In The Court of the Crimson King)
peace & love