I was putting together a demo orchestral piece the other day, and wanted a better sounding alternative to TTS-1 - I came across this collection: https://bigcatinstruments.blogspot.com/2014/08/gm-midi-instruments-for-kontakt.html While some are not anywhere near the quality of the commercial orchestral libraries, most sound far better than any GM/GS/XG instrument. As they're free nki's, as usual the full version of Kontakt is required.