At max overclock the 980Ti is slighty faster than a clocked 1070 but slower than a 1080.
This may change as new tech comes in, especially VR and maybe DX12, I think pascal is very heavily maxwell based so I don't know that a 1070 has much of an advantage over a 980Ti in DX12.
There's no way I'll be spending the kind of money to get a 1080.
Today I was going to buy a 1060 MSI Gaming X but then I seen this offer. What stops me immediately buying the 908Ti is the concern of noise, temperature, warranty (Zotac, not the 5 years) and DX12 performance. Should I not be concerned?
Then again, if I could justify a 1070 I would get one of those. I cannot currently say they are worth it for me sicne I plan on sticking with 1080p for a long time. I do think I'll be trying out 144Hz soon though to hit higher FPS on less intensive games.