I guess I don't have just one favourite band. I love music in general and my 'tops' are changing a little with time, depending on various situations, my mood, things like that... :)
But if I had to chose my absolute music loves - it would surely be L'arc~en~Ciel (with Hyde, the vocalist, as my total nr 1), Luna Sea and Kiyoharu (清春).
Have you ever heard of them?
If not, I would definitely recommend you some of these. Luna Sea are more 'rockish', Kiyoharu is... well, calmer, I guess - and you can find almost everything in L'arc~en~Ciel.
It chanced that they are all Japanese but I don't really limit myself to j-music. I tend to listen more rock or rock-alike music - but I like pop, classical, atmospheric jazz and blues, even electronic as well. And the country origing doesn't matter at all :) In fact, I love listening to artists from all around the world - singing in various languages.