http://www.bmwblog.com/2016/12/04/to...vs-audi-tt-rs/
http://www.bmwblog.com/2017/01/02/au...-rs-vs-bmw-m2/
http://www.quattrodaily.com/audi-tt-rs-vs-bmw-m2/
Haven't seen a review yet that picks the TTRS over the M2, having driven both on the track and the road. Some call it faster (although without track time comparisons), but they don't call it better. They pick the M2. And they pick it for versions of the same reasons--more fun and rewarding to drive.
Look, the M4 is "faster" than the M2. But on some tracks, it's slower--that's been demonstrated. I would not be surprised if the same were true of the TTRS. But in any event, there is no possible way the TTRS, as described and compared by those who have actually driven it, is a no brainer over the M2, as some who post here would have us believe.