Maniac Mansion
The Secret of Monkey Island
Monkey Island 2: LeChucks Revenge
Full Throttle
Am I bring lame by going with four LucasArts games? Maybe, but whatever. Maniac Mansion and at least one of the first two Monkey Island games are inarguable, in my opinion. Im putting Full Throttle in as well for having such an amazing settig and atmosphere. You really get the sense that a short series could be made out of it.
Unpopular opinion: Grim Fandango is probably my least favorite of the LucasArts point-and-clicks.
Honorable mentions from LucasArts include Maniac Mansion: Day of the Tentacle and Sam & Max Hit the Road.
Only guy on the entire internet thinking about the Scoobyverse.