-hiragana (if a jp bank) aliasing at least
-correctly recorded pronunciation for whatever language. i can be pretty forgiving about some things but when the vowels are just completely wrong then no.
-really good oto (which is why i don't let other people oto my banks)
-broad range (not always, but i prefer multipitch)
-vcv for any language. i do have some cv vc banks but i barely use them.
-pitches that BLEND. too many "kire" banks have got a loud belt and then the rest are super quiet and the bottom pitch is whispery it annoys me to no end like there's this thing called a chest voice.
-end breaths (i would prefer if the bank had these, but if not, i can live without them)
-extra sounds in general for fun or useful for other reasons like vc add ons, extra appends added in, whatever.
-mostly decent quality. as long as i can mix out any bg noise then it's fine.
-not too nasally. my banks can get nasally and i'm more forgiving if it's a loud/belting bank or pitch, but if that's just the voice and the nasal overkills it then no thanks.
-unique voice that can be identified with the character. which is why i'm ok with voice acting. i hate when the voice is so generic and boring it just sounds like every average overseas bank.
i think i covered everything?
i'd also prefer if it screamed or growled. like, death voices, not that rikimi sh1t lol.
not a requirement, but it'd be a nice extra
sh1tty frqs can be annoying, but can be fixed so i can forgive them or just re render them with old resampler.