Tone Rion , I love her nasal twang and her ability to transition from high to low notes very efficiently. Sometimes I feel Rion gets the short end of the stick when it comes to "being HQ" because people mistake the nasal for roboticness and or engine noise when she's actually a very HQ voicebank. I also love her design cause it's pink everywhere and I love pink.
Macne Nana , Well when I returned to the fandom after my break I learned about Nana and thought she was an UTAU (which is partly true) and so I grew a liking to her. I loved Nana's voice and design instead of one or the other. When I found out she was a VOCALOID as well I was very pleased because the Macne store was down and I couldn't get her 2S. I heard her voice on V3 for the first time and at first was shocked cause her voice used to be so powerful. Then I looked at her original demo and how she had a squaky voice and remembered Macne wanted to make it sound as close to the original as possible. I also absolutely love her English.
Kokone , I know people say she sounds like Gumi, but I personally don't hear any similarities at all. Her falsetto intrigues me as well as her design. Kokone's concept also makes me like her even more because instead of playing to stereotypes and saying only men can achieve falsetto Internet made a female falsetto.
Anon and Kanon , I love their twin concept, their voices, and their designs.
SONiKA , yeah she has many glitches and bugs, but with work she can sound amazing. Her design choices are good as well.
Gachapoid , I love his voice. and his cuteness, and his design, and concept and everything about him.
Big Al , deep voice which is sexy and I like his design. Enough said xD
SeeU , I do like SeeU a lot and think she's a great VOCALOID, but the downside is her flat voice and boring tone. I like her extra phonetics, but those are hardly usable without a ton of editing.
Camui Gackpo , I'm not a huge fan, but his voice type is bearable to listen to.