Chihiro Onitsuka - good ballads
Gackt- simply great music
hitomi - little rockish
Sonim - good music
W - cute
hiro - amazing voice
Rikki - bit traditional but great
Yo Hitoto - i cant describe her, she hasn't a certain style
See-Saw - some really good songs
T.M.Revolution - he's bit into trance
and my best recommendation would be miyavi, but he's rockish, though his latest single Senor Senora Senorita is latin pop