I like lists. Lists make me happy. Fairly self-explanatory title.

1. One For the Vine - Genesis
2. Pictures of a City - King Crimson
3. Telegraph Road - Dire Straits
4. The Musical Box - Genesis
5. Tarkus - ELP
6. Old Wild Men - 10cc
7. Epitaph - King Crimson
8. Without You - Asia
9. Romeo and Juliet - Dire Straits
10. Anyway - Genesis

A few other close candidates - The opening of 'Dancing With the Moonlit Knight' by Genesis (along with The Light Dies Down on Broadway and maybe Firth of Frith)
Two by Steve Hackett - Ace of Wands and Lost in Time in Cordoba.
Wall Street Shuffle would be on there if it stayed at the level of the opening.
Something by Pink Floyd, but I haven't listened to it enough to decide which is my favourite.
Moonchild (the most stunningly beautiful opening to any song. ever.) and 21st Century Schizoid Man by King Crimson.
Brothers in Arms - Dire Straits
Break on Through - The Doors

I don't expect everyone else to have this weird a list.