My top five:
1.
Quest for Glory 2 VGA
2.
Indiana Jones and the Fountain of Youth
3.
King's Quest IX
4.
Rise of the Hidden Sun
5.
Star Wars: Shadows of the Empire - The Graphic Adventure
Fountain of Youth was previously #1 on my list, but I'm a bit worried about them since they've been promising to release a demo "soon" for over a year now.