This is very relative, but I'll throw it in. To date Maxxis has the"stickiest" comp compound tire available. Krawlers are a close second, with MTRs (again Comp compounds) right behind. I've run all 3 with comp compounds. The Claw is right up there also.
There isn't a Super Swamper that comes close! If there was you'd see them in comps, even if you had to buy them.
If you're talking about a compound that you can readily buy at a store, then again I'd put Maxxis, followed again by the BFG (Krawler) at the top. I've seen them hook up when IROKs were spinning. Again, I'd go with the MTR over the IROKs. TSLs are fine, but old school technology.
JMHO, except for the comp compounds, and those I've tested and seen tested side by side.