The best acoustic guitar recordings??

A hearty second to Edorr's recommendation of Ralph Towner and Egberto Gismonti on ECM. I am especially fond of Towner's work in Solstice and Gismonti's recording, "Silencio" with Charlie Haden.

Also worth checking out are recordings of various Robert Fripp projects (e.g., League of Crafty Guitarists).

Richard Thompson should be mentioned, although I'm not all that big a fan.

Sorry, the Gismonti recording I had in mind is "Magico" with a Haden composition called 'Silence'.