Weird, I fell in love with SNK thanks to diverse style of musics in their games, although different games has focus on certain genre.
Personally I've never understood appeal of Guilty Gear soundtracks. In general I'd say metal doesn't really work in video games. Guilty Gear has this problem, that it is really neutral sounding. It's just background noise to me. Just by listening soundtracks, I'd say that Korean soundtrack of X2 #Reload is better sounding, but I don't know how well they work in-game. Korean OST sounds more video game-y.
Personal surprise for me has been musics in Dead or Alive. I don't know what exactly I find appealing in them.