My favorites are K.K. Soul; Caf? K.K.; Forest Life; I Love You; K.K. Love Song; K.K. Ragtime; K.K. Milonga; K.K. Sonata; Spring Blossoms; and K.K. Swing.
My favorite is I Love You.
When my boyfriend of 4 years+ first introduced me to Animal Crossing, he let me borrow City Folk until I got the guts to buy my own. The first night, K.K. Slider was in town, and he showed me how to do things and request songs from him, and the first one he requested was I Love You, so it has sentimental value to me.
Bubblegum K.K. is a close second - Because when I first got New Leaf for my birthday, the first villagers house I ever visited was playing that song.
Well before New Leaf and only knowing the series from Brawl my favorite song was Go K.K. Rider! after getting New Leaf I really liked Bubblegum K.K. after hearing it at a dream address, then various caught my ears Steep Hill.
But right now my favorite song is no other than the fan favorite K.K. Disco, even Nintendo used in on Isabelle's birthday video
After listening to all of them in my search to complete the collection, I have quite a few favorites!
I love the solo in K.K. Metal. And I love K.K. Stroll because it features my favorite villager Alice! Still, the one song I could probably listen to all day is K.K. Ballad. Not sure why, but it doesn't annoy me after a while like other songs would, like Stale Cupcakes and Neopolitan. *shrug*
I like quite a number actually. Soul and Bossa are recent favorites, but I've always liked House and Stale Cupcakes. Condor and DJ K.K. are really good too.