If I was asked for my favourite movie, or TV show, or song, I would struggle to pick out just one.
Not so with cartoons!
The greatest cartoon ever made (by miles) is Scooby-Doo:
The show (in various formats) has been on the go since 1969.
There were a few missteps along the way for sure (Scooby-Dum and Scrappy-Doo are standout examples) but I would still sit down in front of the TV if I found my kids watching an episode.
Aside from the original series, I think my favourite contributions to the franchise have been the "direct-to-video" movies, starting with "Scooby-Doo on Zombie Island" in 1998.
Congratulations to William Hanna, Joseph Barbera and their team.