When I tested my mother's Christmas build with a 1070GTX against my 980Ti (same RAM, same motherboard, same i7-6700K CPU, same drivers, though I was running Win10 on the 1070 system), they were very close in performance as you moved forward from DX9 to DX11 effects and started ramping up things like anti-aliasing, anisotropic filtering, etc. The 1070 just had better overall internal optimizations for the high-graphics-memory use cases. In some instances, the difference was non-trivial. The 1070 is definitely a better deal, with an almost 33% discount vs the 980Ti.

980-vs-1070.png

I didn't save the images from the DX9/1080p tests in older games but suffice it to say that the 980Ti heaped scorn and shame on the 1070 in those tests. That said, we're talking a difference of 60min/130max(1070) vs 95min/330max(980), so even with that enormous disparity, you still aren't going to be crying about it.