I would recommend Cosmo@Bousou-P if you like fast songs, if not, you maybe find something interesting in his old releases.
Atena is really good beginner artist. Mostly Atena posts music with Vocaloids that being used less than popular ones. It's has really fun and happy vibe with little bit of weird core.
Next one is john. Posts vocaloid and really good j-pop (also known as TOOBOE). Has really interesting combinations of sounds would recommend! But lyrics and music videos may be disturbing and triggering!