Welcome, enter your question. Please start with words like "Who, What, Where, When, Why, How, etc..."

But for content purposes, we can provided a reason below.

Note Please view the individual Vocaloid pages on the Vocaloid Wiki, the section for popularity gives some insight. And unless you are specific the term popularity can be many things, such as "Popular by...":

  • Usage
  • Songs
  • Voice
  • Gender
  • Avatar
  • Origin (company)
  • Sales
  • Listener stats/views

When it comes to companies viewing which of their Vocaloid products sale compared to others, that counts as popular to them. In addition there are professional musicians who never post their work on popular websites like YouTube or NicoNicoDouga, choosing to use Vocaloid as it was intended to be used.

However, in an attempt to answer this question based on fandom reactions, it's the Japanese Vocaloid, (Gachapoid) Ryuto and the English Vocaloid, Tonio that would appear to be the least popular.

  • Utatane Piko, (Gachapoid V2) Ryuto, Kaai Yuki, Hiyama Kiyoteru, and Tonio for usage.
  • Leon, Lola, Sonika, and (V2) Lily for voice (said to be difficult to work with)
  • Sweet Ann (original), (Megpoid V2) Gumi, Ring Suzune, Hibiki Lui, and Aoki Lapis for avatar.
  • Meiko, Kaito, and Miriam for sales, likely due to being Vocaloid 1s.
  • English Vocaloids in general, do not receive as many views as their Japanese counterparts.
See also