Depends on my mood. I love KK Fugue, Sonata, Jongara, and Jazz. I really want to hurry up and earn Brewster's Brewstoids, change them out on stage, and choose some songs with them as a background. Should be really great for laughs, as someone once said on this forum!
You know, I hated K.K. Idol / Bubblegum K.K. when it was revealed for ACNL - so much so that I didn't bother learning which name was the English / which was Japanese.
Buuut I watched K.K. Slider perform it on stage and it was fuuuun. I still don't listen to it in any of the rooms at home, but I've requested it on Saturdays a couple of times
edit: Looks like I need to request this K.K. Jongara some time.