I never really got into Miyavi, but I know who he is as I've had a lot of online friends that listen to him. In terms of Japanese groups, I'd say that my favorite song would be
Cube ny Gackt.
In terms of actual favorite groups/artists though, it would be Blur first and always....
But I also listen to Andrea Bocelli, Coldplay, Deadmau5, Franz Ferdinand, Garbage, Gorillaz, Jean-Michel Jarre, Muse enough that they'd round out the top 9 in no specific order.
Oh and I agree with the be respectful thingy. Only my mom gets to say that my taste in music is crap. She pretty much likes the Rolling Stones, AC/DC, and just about anything from the grunge genre.... and hates just about everything I listen to.