The spinoff to the first Parappa game. The music is so much fun, and the switch from rapping to guitar, allows for more complicated rhythms to keep up with. Because of that, this ends up being the hardest game out of the 3 in the series. And I honestly like that since both Parappa 1 and 2 are honestly so easy that it's hard for me to come back to them often.
Also this game's story is so batshit insane. I love it so much.