My top Yabby You recs:
The Prophets - Conquering Lion (Yabby's debut more or less, and a great backing band featuring underrated drummer Leroy "Horsemouth" Wallace)
And going off of that, you'll probably want King Tubby's Prophesy of Dub, which is mostly derived from Conquering Lion. For me, a top-five dub release (can't go wrong with Tubby, generally).
Then I would also rec Yabby's Deliver Me From My Enemies, w/ Sly & Robbie and otherwise another great band. The reissue of this record off of the Blood & Fire label has lots of great bonus tracks, as well.