Alborosie provides the cleanest roots rock since The Wailers, Peter Tosh, and Jacob Miller. Shuffle his music on Spotify, you'll be surprised how many great songs he has. And if you like reggae, you'll probably hear some songs you've jammed out to before. If he ever comes to the states you won't want to miss that show.
Secondly, Popcaan...a Jamaican dancehall artist who recently released Where We Come From - pure gold from start to finish. You can stream it all for free here. Happy listening!