Here are my favorite songs based on solo & duet Vocaloids (minus Meiko):
1. Hatsune Miku: Meteor/ VOiCE
2. Kagamine Rin: Delusion Sketch/ Liar Betty
3. Kagamine Len: Here Come Karakasa-san
4. Megurine Luka: Dye
5. Kaito: The Sun in the Night Sky
6. Miku & Kaito: Cantarella
7. Rin & Len: Like Dislike
8. Miku & Luka: World End Dancehall