Hiya! Pupu here! I know I said that I'm on hiatus but that doesn't mean that I can't come here once a day to check possible alerts
I gonna suggest some of CVVChinese what I know:
I have heard that 磯子Ruby/Isoko Ruby has good pronouncing plus nice voice but sadly she's like a Matsudappoiyo: If I remember right, she's only downloadable in creator's birth day - no on other days. I think that Chinese people would know better the date when she's temporarily available, I don't know, sorry.
青音ガイ/Aone Gai is Furry but he has a very nice male voice. Kaibara Daiki/海原ダイキ is a great male voice too.
And I recommend any VOICEMITH's UTAU (Xia Yu Yao, Oscar and Joan). Their latest VB has proper oto, multiple pitch/append plus HQ voice quality. I must say that Xia Yu Yao has "Taiwanese accent" and that all 3 has "custom alias" of "V C" sounds: not same than in other CVVChinese. However! This all 3 latest VB comes with a plug-in that makes using them more easy.
There's only 3 known Chinese VCV VBs: Ring, Ryone Yami and Kuuki (空気) + there's a plugin to help using VCV Chinese. They are all one pitch only because recording one full Chinese VCV is as much work as recording 10-12 pitch Japanese VCV. I don't say that they're bad but I won't recommend recording Chinese as VCV at all! 3 pitch CVVChinese is a much much better option than one crazily big monopitch VCV plus I've heard from native that there's no much any smoothness difference between CVVChinese and VCV Chinese, so...
CVVChinese > VCV Chinese
And there's few VB that aren't recorded in standard CVVChinese reclist nor VCV but are still great voice wise (their encoding can be very different comparing to other Chinese VB's, be aware of that):
Hanami/花見 <= IDK what reclist is this but she sounds very smooth and nice as being oversea UTAU.
and
Kumaka Lika/熊歌リカ <= Simple CV-like VB with "VC R" settings for sounds like "bai" "ban" "bang". This type VB is easy for beginners to record.
I hope that you find this post helpful! Good luck with Chinese!
Ps. Did I remember to mention that Delta's Auto-CVVC ver 2.0 plugin actually supports CVVChinese?