"Super Ape" and "Arkology" are great selections. There are also a couple of good 2cd Scratch comps on Trojan that include the dubs - "Build The Ark" and "Open The Gate". Also on the Lee Perry side of things "Blackboard Jungle Dub" is fantastic but be careful which version you buy as it has been fucked around with and rebranded a bit over the years by uncaring hands.
"No Bones For The Dogs" which is a Joe Gibbs / ET compilation and is to my ears infinitely preferable to the slightly lightweight African Dub sets. Vol3 is ok, great in parts and a bit of an iconic release in punk / rock circles. Can't hear it myself not when compared with "Brand" which is a heavier record in every respect. Though the "Chapter Three" track from "African Dub Chapter 3" itself is pretty essential and a great revisioning of the "King Tubby Meets Rockers Uptown" rhythm complete with sound fx.