Both.
J-pop, there is my mega favorite artist : Ayu. Besides that, I really like J-pop lyrics, some of them are really meaningful, and the lyrics also have playing words which is really fun!
K-pop, I basically like the songs, dances, their stories, their concepts.... but the lyrics are almost love-themed...
and even when I only like just a song from a group/singer, I could consider myself as their fan, but in J-pop I couldn't do that. (Dunno why too!) Their CDs are also affordable LOL