Too many to name... and I go through phases...
X Japan was the first album I bought (Dahlia) and I went through a mini visual phase around the time of hide's death (X, hide with spread beaver, L'arc, Luna Sea)
But I tend more toward the pop rock/band style, and the strong male/female ballad/folk singers... Mr. Children, Spitz, Bump of Chicken, Remioromen, B'z, Ellegarden, Glay, GReeeeN, Love Psychedelico, Monkey Majik, Porno Graffitti, Radwimps, The Yellow Monkey, Mongol800, Fukuyama Masaharu, Moriyama Naotaro, Yamazaki Masayoshi, Ayaka, Hirahara Ayaka, Teshima Aoi, Hajime Chitose, Hitoto Yo, Salyu, etc etc.
And I don't watch so much actual TV these days, so I am about three years behind on new artists... I officially feel old :)