VOCALOID
Vocaloid is awesome because anyone can make music with em and you can make them say anything. By anyone I mean people who BUY it duhh. I guess the free version of them is utauloid but theres less features.
Utsu-P【鬱P】- GREATEST SH*TS
Look at this cover art!! beautiful... Anyway Utsu-P makes the greatest metal songs for vocaloid. I love guitars too much. I haven't analysed the lyrics and I probably won't ever so you know how it is. I barely found out about them in late January. My favorite songs from this album are THE DYING MESSAGE, Anti-Digitalism, Attack!!, Corpse Attack!!, Black Hole Artist, and The Magic of the Massacre. You can listen to em here. I like the freaky-sounding voices that come out sometimes.
livetune-Re:Dial
Took me a while to find out that livetune was actually a band and not some special version of songs. I like the uhh electric sound of their voices. I don't know how else to describe that tone X_X. My favorite songs are DECORATOR, Redial, and Tell your World. I really like the music videos that come with them because they use lots of colors and Miku dances well in them.
DECO*27
They make Miku sound good and the melodies are catchy. My favorite songs from them are Habina, Ghost Rule, Cowardly Montblanc, Otome Kaibou, Love Words III, and Reversible Campaign. There might not be music videos for the songs, but the art that accompanies them is always lovely.
Yuyoyuppe
Not really familiar with him, I heard that he was the writer and producer for some songs for Baby Metal (mmm yea!). He makes good use of Luka and the guitar. I would describe the songs as more uhhh metal. Not for the faint of heart.