if mikoto and hime were on here they'd be SS tier for sure...
(each tier's characters are in no particular order)
miku: most range out of any vocaloid
lily: hot when tuned right
gumi: most realistic
luka: beautiful when tuned right
yuki: most unique
iroha: nice tomboy-ish yet feminine sound
anon: not unique but very pleasant
flower: popular for a good reason (although i used to hate her)
una: have never heard her tuned badly
VY2: best male vocaloid
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IA: nostalgic and pretty
SF-A2 miki: cheerful and charming
gakupo: has the potential to sound very realistic
seeu: cutest design and unique pronunciations in japanese
nemu: most unique right beside yuki
uni: cute design and voice
oliver: the best english vocaloid
cul: pretty when tuned right
chika: charming, similar to gumi
matcha: somehow both young and mature, somehow both girlish and boyish
VY1: distinct, powerful voice
rana: very recognizable
rin: iconic
len: also iconic (has grown on me over time)
lapis: a true moe voice
piko: extremely good range
rion: good for fluffy songs
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kaito: he can sound good but it takes a masterful tuner
yukari: a bit boring but pretty
meiko: fun to listen to
kiyoteru: sounds nice, i think he has some sort of rock voicebank
fukase: overrated but has a cool sound
mayu: good for calm or cutesy songs
bruno: surprisingly very good
macne nana: prefer her utau voicebank
cyber songman: idk why i put him so low, i just relistened to him and he's extremely good
that green kid: good for jokes and experimental songs
zunko: can produce very pretty harmonies
ruby: one of the best english vocaloids
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galaco: odd but has her good moments
sachiko: love the concept, but sounds muffled
mew: kinda basic
yohioloid: just a guy
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sonika: incredibly muffled
merli: also basic
cyber diva: sounds pretty weird
kanon: a little annoying
big al: can sound cool if you're going for a scary sound
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clara: not a fan
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this girl: i remember not being a fan
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those two at the bottom: also not a fan
in the end, any vocaloid can be used right...
make one for yourself! : https://tiermaker.com/create/vocaloid-tier-list-4067