The Vulture article in this thread's OP makes the bold claim that Genndy Tartakovsky is the world's greatest living action filmmaker.
It was right.
I think in the in overall quality in the animation industry, Gendy is probably the hardest to top because he can do action, and just pure storytelling by movement. But when it comes to pure action there's stuff like the DMC3 Cutscene director whom is phenomenal and probably the top of that field, and there was indie people like the now passed Monty Oum who was close to that level but closes the gap with a crazy eye for creativity.