Len append was probably the ones banks' set of him I like (especially Serious and Power, though Cold is cool too) and he and Rin are inseparable + I love the song ARIA by Yunosuke
Piko is cool for heterochromia and androgynous voice + really good match with Miki and not only because of their ahoge + when GEN applied he doesn't sound distorted, which is cool too + PIKO!human seems really adorb'
Gacchapoid is nice because it must be cool for some people seeing their childhood hero turning into a Vocaloid + the box was cute with the goodie inside of it
Big Al is one of the best for low ranges and outstands well both in design/concept and voice + the funny "I'm too sexy" cover meme is just fantastic
RUBY conveys well R'n'B songs' feel, and hip-hop as well
Common good thing to say about them : at times depending on the way people use them, they earn a few points back in my esteem and whereas I'm not a huge fan of them, I still feel they'd lack to the whole VOCALOID range if they haven't existed