I like KK Synth, but I'm also digging the KK Etude / KK Sonata type ones too. I don't really like super upbeat music in my house, I like it chill~ but I don't have a stereo in every room so I've basically been listening to Stale Cupcakes over and over and over every time I come in the front door and damn if that doesn't get old after a while.
I love Marine Song 2001 (I think that's what it's called?) because I'm a sucker for all things nautical, and Forest Life is okay too... I think I need to actually hear all the songs before I can pick a favorite, but those are all ones I like a lot so out of what I've heard so far.
My personal favourite is Neapolitan. Whenever I hear it, I feel like I'm sitting in front of a fire on a cold winter's day. It was actually the song that made Erik one of my dreamies.
I'm also a stickler for KK Aria, Stale Cupcakes, Steep Hill, Se?or KK (only in specific rooms, though, like a cafe), KK Salsa and KK Condor.