I would support Mike Green, of Realivox... but not the link Larry provided... Mike's latest creation, "Blue" is amazing... and only $129... he is an active developer, has responded to me and others I know personally and immediately...and is actively plowing more "vowels/consenents/combos" into his creation as he gets the money from sales...
Blue does all the ooooos and ahhhhhs you can imagine and much more. It is quite lovely. Mike has hadded several new vowels and combination utterances since I bought it... he's a real guy, not a "company" or "corporation"
http://realitone.com/blue/.
Just listen to the soundclouds and the walkthru... and remember it is an actively evolving library... which will grow with you as you are entitled to updates as long as you live. It runs on both Kontakt and Kontakt free...
I own all the EWQL libraries... their choirs are nice but a thousand years old and the "word builder" system sucks...I also have several 8dio choirs... Meh...
Enjoy your search...