I can’t comprehend their list. I would put “The Secret Of Monkey Island” in the first place. Reason: The story is one of the best written stories in the adventure history. The puzzles fit (mostly) perfect into the story and the game has this great and subtle humor.
I can’t. 
For me, Grim is one of the most overrated adventures. The story is great and well written. But the controls were weak (i only say “the elevator puzzle”), the graphics were “sterile”, the camera positions aren’t good and the puzzles were, well, Tim Schafer, puzzles. 
It surprises me more that the “The Last Express” is at position 7. I only liked the graphics style of that game … (is The Last Express an adventure game at all?)