It used to be Go K.K. Rider, but while designing a house in HHD I happened to be struggling to find inspiration in one villager's house (I think it was one of the monkey villagers). Though I'd already added a stereo and Steep Hill just played and played and it turned out I liked it a lot. It's really chill and helps me to relax just hearing it in my head even.
K.K. Cruisin' (it has a slightly trip hop-like feel imo)
Forest Life
Marine Song 2001
Go K.K. Rider!
Rockin' K.K.
K.K. Marathon
K.K. Groove
The K. Funk
I love the songs Forest Life, My Place, and K.K. Disco. Space K.K. is on there too.
I once had a room in the museum where there was a QR code design of a butt and I refurbished furniture with the design and played "K.K. Parade" in the room. Yeah. When I rediscovered it a few months to a year later I just about died laughing. It was too much for me.
K.K. Rockabilly. It was the first song I ever heard from K.K. Slider so I guess I'm biased, but it's so catchy too! I also like Marine Song 2001 and Forest Life.