I have both 1070's and 1060's in separate rigs mining Ether, and here are my settings and results with stable 24/7 mining:

GTX 1060 6GB
No chassi fully open build.
NVIDIA driver 382.05
MSI Afterburner power limit 60%, core clock +150, memory clock +750.
With Claymore miner 9.7, the hashrate is 20-21 MH/s and power draw is 103 watt. Temperature at 64 degrees celcius. Fan speed at around 40% (pretty silent).
Efficiency level 103/20 = 5,15 W/MH

GTX 1070 8GB
In a big tower chassi.
NVIDIA driver 382.53
MSI Afterburner power limit 60%, core clock +150, memory clock +700.
With Claymore miner 9.7, the hashrate is 29-31 MH/s and power draw is 130 watt. Temperature at 66 degrees celcius. Fan speed at around 44% (fairly silent but audible in my room).
Efficiency level 130/30 = 4,33 W/MH

So... depending on how fast you want ROI, your budget, watt prices and other factors such as power supply unit(s) needed, wife complaining about noice level and heat etc , you need to decide what you think suits you best.

Personally, I really like the 1070 cards for their power/MH efficiency level and low noice. I've been able to buy my 1070 cards for around 490 USD on second hand markets (unused retail price is 650 USD in my country).

Hope this post helps. Cheers and good luck!
/Arch

PS. I previously had GTX 970's and I got an efficiency level around 7 W/MH (17-19MH/s).