cryptonight = 450 vs 690
neoscrypt = 500 vs 1000
So
if you run Cryptonight hashing, the four 1070 cards will produce 900 more hashes vs six 1060 cards
if you run Neoscrypt hashing, the four 1070 cards will produce 1000 more hashes vs six 1060 cards
So yes, its better to run four 1070 ti cards than six 1060 cards!!!!!
have you ruled out AMD cards completely? currently RX480/580/570 will get you around 22 Mh/s EThash or 700 H/s cryptonight so significantly more than the Nvidia ones for cheaper.... I do understand some people are "just Nvidia" for some reason
I prefer nvidia for reselling reasons and the less power consumption
I do had ATI in the past but when i moved to nvidia just for a try then it was no turning back, nvidia = quality (that was on the gaming part, but still i value more the nvidia).