There are lots of great choices. To some extent, Renbourn's tendency to wander through widely differing styles will dictate which records work best for any given listener. His earliest material is pretty much straight folk, then there was a period of Pentangle's "folk baroque", followed by several years of more classically styled compositions. He even did a movie soundtrack with John Paul Jones of Led Zep.
Personally, I have a soft spot for "Bert and John", the Renbourn/Jansch collaboration that preceded the formation of Pentangle. The songs are strong and the playing is magnificent on the part of both guys. Anyone who loves acoustic guitar should hear this one. However, your own tastes may ultimately take you in another direction.
BTW, some years later, the album "Bert and John" was re-released under another title, so you might do a quick search to see which is available at the best price.