I never knew such software existed!

To me Blue is the best sounding, but it does take some work. Getting any reasonable approximation of the human voice singing is about the toughest thing to do. You need to play around with timing and legato of which blue has several. Fortunately Mike Greene who is Blue's creator is a great guy and very responsive. He also runs VI-Control these days so he's pretty easy to get a hold of.
 
This is a brief attempt I made a while ago. As the nice folks here will tell you I'm lightly skilled at best and you can do better, but this is an idea of a newbie using Blue.
https://soundcloud.com/bi..1969/amazing-grace-blue

I went to Realvox, and the August special for Blue is still available for $119.00.
 
http://realitone.com/blue/

OK, been doing more reading, watching videos, and testing / trialling.
Realivox Blue seems to be the closest/best for what I want to do, but as mentioned above (and on the demo video), it still doesn't have a complete set of sounds/vowels/phonemes, so it struggles to produce some words.
The demo video is very interesting where he changes the word structure; often putting the end consonant of a word on the beginning of another - that certainly improves some phrases. 
I guess it's a tool they requires a lot of practice to learn to get the best of it (and people say we should stop messing around with computers and take the time to learn to play a 'real' instrument 😀 - 'playing' a PC is just as hard, and requires just as much skill/practice - it's just different).
 
I totally get that the number of hours put into creating Realivox Blue must have been phenomenal, but I'm struggling to understand why they've gone on to produce a newer product (Ladies) with more voices but less syllables? From my perspective, I'd rather a single voice with more syllables......
 
Anyway, as always I appreciate the feedback and suggestions from here (without this thread I would never have known Realivox existed). Not sure if Blue will be my final purchase, or I'll wait to see what 'comes next', but it's interesting (and amazing) to see what is possible.
 
.....and my worry is if I get out the credit card, I won't be able to resist my rising urge to buy RealiBanjo as well 😀

I prefer The Ladies for the kind of stuff I do, which is mostly background chorus ooh-aah duties. Although it has a more limited vocabulary, having multiple singers with distinct qualities results in a more believable ensemble.

You can use standalone . But It is an app for Cubase DAW.
Zero-G vocaloid pack
https://zero-g.co.uk

oockkk
You can use standalone . But It is an app for Cubase DAW.
Zero-G vocaloid pack
https://zero-g.co.uk

They're not specific to Cubase. The Vocaloid application they run in is, however, specific to Windows (7 or higher), which actually eliminates half of Cubase users.