1080 is no good
On equihash
1060 270/sec
1070 430/sec
1080 ti 635/sec
On amazon current prices
1060 $300
1070. $500
1080 ti $750
Rate / price
1060 .90
1070 .86
1080ti .85
Assuming the above are correct the 1080ti is the best bang for the buck.
You also have to consider what scale you are going to mine on. Motherboards, power supplies, risers, etc are not cheap. One rig with six 1080ti would certainly be more cost effective than building two rigs with six 1060.
Is there any difference, between OEM brands??
Because some time, price difference is more then 100$...worth to pay?!
Other available markets,beside Amazon?? nwegg is "out of stock"

(
Thanks in advance...