To answer your question tho, I suggest go for the 1060s only if you're planning to build a large rig (more than 8+ GPUs). Otherwise, if youre using an existing PC mobo with just 4 GPU slots for example, just get the 1070s. 1060s because they are more power efficient in terms of hashrate/power-consumption and they are easier to resell. Not many gamers are willing to spend on 1070s when 1060s do the job well.
I would suggest go with a "traditional" 6 GPU configuration since most of M/Bs have 6 PCIe slots. More slots mean more power for GPUs that will lead to 2 x PSU.
Bad advice. Do you think sticking to what is traditional will get you maximum profits? If you keep doing what are you doing today, you will never get anywhere. You should really learn to have an open mind and try and change for the better.
Your "more slots and more power for GPUs" problem can easily be remedied by an even more
power efficient server PSU. Server PSUs are also cheaper than your regular PSUs.