Comparable on paper perhaps, but Nvidia architectures tend to get more actual gaming performance per FLOP than AMD architectures do.
i.e. the AMD RX480 (5.8 TFLOPS) is 30% faster than the NV GTX1060 (4.4 TFLOPS) on paper, but in practice they perform more or less the same.
Even in titles where AMD performs especially well the advantage is around 10-15% in favor of the RX480 - still less than the specs would suggest.
https://www.newegg.com/Product/Product.aspx?Item=N82E1681412...
aside: That was my personal golden age of gaming... Intel had an OC-48 to SC-5 building... so playing UO on 6 machines simultaneously when everyone else was modeming at 56K made us like gods against lag in that game... I still think fondly of that time.
This is a very good explanation/speculation which deals with the NV driver optimization for DX11 where they break up the draw calls between threads because the scheduler is software based where AMD is hardware based and can't do the same. In DX12 this isn't needed so AMD scheduler being hardware based can be better utilized.
Of course that since my foremost interest is computation, then NVIDIA it is. But if you just want to game, AMD gives a better bang for the buck.