I think Katt will vouch for me on this, but if you're interested in the "outlaw country" genre, dig further into Waylon (that man can play guitar for real), but if I was to recommend one album, it would be "Kristofferson", his debut. More mellow than Waylon, but it's an intense listen and really has the philosophical roots of the genre. It's also got the original version of "Me And Bobby McGee" before Janis Joplin made a mockery of it (Interesting fact: there is a version before Kristofferson's, by Roger Miller, and Janis came to know the song when Kris played it to her directly. They were banging at the time.)
Hank, Jr. is always good, too, but he's got a LOT of filler in his catalogue. I'd stick with "The Pressure Is On" for an original album, or a greatest hits package.