1070 have more option for sure, with amd you are stuck there mining ETH,if ethereum sink what you will do with amd gpu? nothing, there is only monero which is not profitable, other algo are not optimized or the optimization is private
you have got your information wrong, with amd you can mine any coin, not so much with NVidia as there is ONLY a small handful of profitable coins along with optimized miners for said coins, the rest AMD still dominates. sure you can mine just about any coin with an NVidia but it doesn't mean its going to be efficient since miner code for a lot of coins when it comes to NVidia are not optimized much or at all, with the exception of a handful of coins like zcash. take ETH for instance you can mine it with NVidia but doesn't make it good, as matter of fact most of the time you get much worse of hashrate with NVidia on eth than say an rx 480, if what you were saying had been true there would be WAY more people mining with NVidia than amd which is not the case