It really depends on the rest of your team, but I'll go out on a limb and say Scrafty.
With access to Dragon Dance and Hi Jump Kick, it's a terrifying sweeper. It's defenses are also quite good compared to most Pokemon but its typing leaves it vulnerable to other Fighting and Fairy Pokemon which seem rampant with Close Combat and Moonblast. That said, both Moxie and Intimidate are excellent and help out a lot. It can even run a Sub-Punch set.
On the other hand, except for Sub-Punch, Poliwrath doesn't stand out too much. Water Absorb is a good quality, but unless you have too many Pokemon weak to Water on your team, it doesn't help out too much. Its stats are better rounded, but that means it doesn't do too well in any thing. It can run a mixed set, but it's not that much better than Scrafty, or at all, to be honest.
I'd say go for Scrafty. Either Sub-Punch or Dragon Dance sets are recommended.
