Personally, I would go with a GTX 1060, as I think you pay a lot more for a marginal performance increase with the 1070. A 1060 should play most modern games on high/max graphics settings, and will be a significant increase over what you have now.
Long story short, unless you have a reason for the bit extra performance of 1070, don't waste your money. Also, prices on 1070 are the highest they will ever be now. The price gap between 1070 and 1060 won't be so big much longer, mark my words.