2005 Pride Grand Prix Shogun vs 2015 DC fight Jones
If they met in the UFC, I'd take Jones to wrestle his way to a decision win, although he'd have to walk through fire early, and defend against sub attempts late. The UFC environment really suits a wrestler like JBJ, and I think his strength and control would gradually wear Shogun down. Would be a great fight.
If they met in Pride, I'm really not sure who would win. The different ruleset and environment would make for a different fight. I can see Jones winning via nasty elbows in the clinch and the occasional TD, but I can also see Jones getting trapped on the feet and being unable to deal with Shogun's ferocious attacks and getting broken down. I think JBJ would find Pride a very different world. Circling away into space from the attacks of Rashad and Machida is just not the same proposition at all as being trapped inside a ring with a peak version of Shogun or (roided to the gills) Wanderlei, where you cant elbow on the ground but can get soccerkicked right in the mush.