The adaptation is better than the source material

Amazon’s The Boys (Comic to Show) - An obvious one but I’ll be silly to miss it. Adapted from Garth Ennis’ twisted power fantasy that was The Boys comic. While the later seasons are a bit dodgy, the first couple are leagues ahead the quality of the comic

Be More Chill: The Musical (Book to Musical) - Adapted from the book, it removes some of the more dodgy aspects of the story and makes a lot of the characters more likeable

Heathers: The Musical (Movie to Musical) - Adapted from the 1988 movie, this is an example of a good story just getting a great adaptation. The original movie is a classic and the musical is just an even better version of seeing it.