Welcome to the forums!
Hmmm... it seems you already have a lot of awesome Sierra classics covered in your list. My personal favorites are Gabriel Knight: The Beast Within, King's Quest VI, and The Colonel's Bequest. But really, I love so many Sierra games, it's kinda unreal!
Oh and nice to see you've got Quest for Glory: Shadows of Darkness at the top of your favorites. To me, this one is clearly the best QFG game ever! Just thinking about Mordavia makes me wanna play it right now!
