The AcousticSamples Sunbird is a great acoustic guitar library for UVI Falcon. It's a Gibson acoustic guitar and is my go-to when I need an acoustic guitar. There are times my place isn't quiet enough to record acoustically and I have to go the vi route. May also want to check out AcousticSamples electric guitar libs for Falcon.
Not all that enthused with any of the guitar libs for Kontakt. Other than the sound what kills vi guitars is the strumming engine. Get that wrong and it'll sound horrid. Also don't try and play a vi guitar like you would piano
