My favorite bands/artists... well, I have a lot of them, but they definitely include:

Lolita23q, Dir en grey, Hyde, Gazette, An Cafe, Panic Channel, 176BIZ, Ayabie, Megamasso, Kotani Kinya, UVERworld, Bis, Art-School, Cannival Method, Danger Gang, Death Rabbits, Gossip, Jinkaku Radio, Kannivalism, Irokui, and Metronome... among many others.

Favorite songs... well my favorite is ishoku osero by Lolita23q.
Other favorites include Umbrella, The Third Empire, Obscure, and Macabre by Dir en grey; wagamama koushinkyoku, merimeikingu, Nyappy in the World, and Maple Gunman by An Cafe; One's Life, Date, 829 Service, Love Letter, and Catch [walk up to the continue] by Panic Channel; Social Riot Machines, S.D.R., Bath Room, and Silly God Disco by Gazette; aaand then a whole bunch of other songs by other bands. Dx I can't pick just one!