This is my fourth favorite Honeyworks song as well as one of my favorite Rin and Len duets so far. Classic. It's an old one with some poor tuning, but the song itself has really shaped the VOCALOID industry and its personification of the libraries.
This is one of my favorite Regulus songs as well as one of my favorite Megurine Luka songs. I remember listening to this just a few hours after it was released.
This is one of my favorite songs by CircusP, EmpathP, and that uses SF-A2 Miki. The English is really great for an advanced Japanese voice bank. Only a veteran tuner can pull that off. The art is kinda wonky though.
This is my favorite song using Tohoku Zunko, one of my favorite Maika songs, one of my favorite Hatsune Miku songs, and one of my favorite CircusP songs. This song is freaking awesome.
This is one of my favorite CircusP songs as well as one of my favorite SF-A2 Miki songs. It may not sound like it, but this song is extremely deep and well-written. Some very valid hypotheses can be found in the comments.