Maro Itoje up there, for me. I think his penalty count last week could see him lose out, though (however I did see a break down of some of his penalties on reddit, and some of them were "for the greater good (the greater good" type penalties, as he stopped a 4 on 1 overlap by killing the ball at one point).
Faletau has been quiet, but quietly effective.
Jon Davies definitely in with a shout, he's been the most consistent performer over the three tests, I reckon. Some VERY important contributions today both on attack and defence.
SOB's been class, too. Really hit his stride again.