While Loom will always have a special place in my heart, DotT is possibly the best all-around adventure game from my childhood; particularly considering that the LA games have aged far better than most of the others.
The funny thing about Loom for me is that I remember the situation and people that were playing the game more than the actual game's story. It was a blast playing after school with a group that argued and explored together. I'm not even sure we finished the thing.
The other adventure games I had played to that point I was only able to finish by playing in parallel with several friends and when one of us got stuck, we would help each other. Hero's Quest was the first game I completed in this manner (we were stuck on King's Quest until someone downloaded a hint guide from a BBS; that game was primarily difficult because how easy it was to get in an unwinnable state).