Here is my list in no particular order....
1. The Longest Journey
2. Real Myst
3. Riven
4. Exile
5. Blade Runner
6. Journeyman Project 2 - Buried in Time
7. Journeyman Project 3 - Legacy of Time
8. Amerzone
9. Darkfall
10. Grim Fandango
11. Curse of Monkey Island
12. Zork Grand Inquisitor
13. Gabriel Knight 3
14. Uru
15. Lighthouse