I was sure that Nexus and Omnisphere had sections in their "legal notices" saying that you can't use them to build your own sound libraries.
The Mystic Kingz Choirz 2 pack demo is playing now on my computer...
Lots of patches are from Nexus, Omnisphere and a couple of singing monk albums (like the one that Enigma ripped off on Sadness Pt2)
The high pitched female opera singer - Nexus.
(There's a stacatto and a gliding version of this voice in Nexus)
Omnisphere - also has a pretty decent selection of choir samples / solo vocalists / Black & White Minstrels - haha!
Then again - Vengeance Sound have loads of legal threats in their libraries saying that the sounds are all watermarked and you can't build loops with the individual sounds and sell them or give them away!
But -> most of the Vengeance samples are ripped from CDs, vinyl anyway without copyright permission.