Haven't played as many games as most of you probably did but enough to compile a list:
1. Gabriel Knight 3, closely followed by GK2 (still haven't finished GK1)
2. Broken Sword - Shadow of the Templars
3. The Longest Journey
4. Keepsake
5. Black Mirror
6. Curse of Monkey Island
7. Overclocked
8. Culpa Innata
9. Syberia
10. Broken Sword 2 and 4
Edit: Hell, I forgot to add Phantasmagoria and Legend of Kyrandia