A nice spin-blocker that can also setup Stealth Rocks? That's pretty much all about Golurk, and that's really nice, as you can keep the rocks up without any need of support at all. It can beat Musharna and other threats, and can be an offensive force at the same time. Choice Band is also nice, but far from being unique, but Iron Fist really makes an edge for Golurk on that, and a Choice Bander able to bypass Musharna and Rocks is quite good.
Golurk is a top threat, and I think he's the best Pokémon of NU, as he can archive more than one objetive at the same time and do each one great. No Guard Dynamic Punch, Stone Edge/Rock Tomb are also nice to annoy and scout, anyway. Also, he looks like a mecha, that gives him some cool points, too.
There maybe some some best offensive and support threats like Braviary over there, but no one is so versatile as Golurk is.