you know i dont use UTAU all that much other than to make my own VBs but i have had the same bunch of banks for ages and i really do like some of them so i wanna recommend some!
CODE:ANNIN_CVVC - hes got four banks i think? i just find him to be very interesting with quite a range. i kinda like the banks that lean on 'messier' sounding samples/recordings so i guess i like him more than some may
Darling - she is one i have had for a long time now! for a while her quality wasnt good but its much better in the new VBs. it seems she has moved more to korean and deepvocal now too. always loved her Crazymoon vb and her tone is so cute.
Origami-I - similar to why i like Annin but to the extreme in terms of recording samples/otoing in untraditional ways, definitely not one that everyone will love. i just like the idea of not having to be smooth, being weird about it, doing something people probably wont like because its so backwards from the super human smooth utaus ppl lean on. however not everyone is ridiculously choppy and breathy, theres this
cvvc oto edit that sounds lovely and some covers like
this or
this i think are nicer too for those that dont like the choppiness.
Spike - ok this ones a bit nostalgia for me because it was like... the second utau i ever downloaded lol. aside from being cute i think hes real high quality. been around for quite a while so i think a more old and now obscure voice deserves some love.