S.L.I.P.
http://www.indiginus.com/
Light on your wallet, big bang for your buck!
Yup - +1 for Indiginus Julien. One of his best releases was not that long ago - the Renaxxance Nylon String Guitar - really nice, right
out of inside the box.
Another is Aria Sounds.
http://www.ariasounds.com/kontakt_instruments.html In mid 2014, I bought K4 off KVR for $120.
Then, last December, I upgraded to K5 for $49.99.
As stated above, I use K4 or 5 [or usually both] in every song now, and I'm starting to wonder how I ever did without it [them].
Others I use are NIs Scarbee Rickenbacker Bass and Session Strings.
You may even get these and many others included in Komplete for an upgrade price close to buying them alone, which is what I should have done.