Claiming eth is the most profitable shows a lack of understanding of the ecosystem overall. I have been mining ZEC for the last 14 months over eth because I run all Nvidia stuff and I dont pay for power. Profitability is a case by case thing depending on a number of factors.
You are flat out wrong claiming its the most profitable to mine on Nvidia hardware.
E.G. - GTX 1070 @ 475 sols = $61/mo
GTX 1070 @ 26 mh = $50/mo
GTX 1070 @ 26 MH/s? Really?
Most 1070's with Micron memory are easily pushing 30.5 - 31.5 MH/s on ETH.
Lets take average 31 MH/s which according to your calculation gives:
GTX 1070 @ 31 mh = $59.62/mo
Now, we get $59.62 at ~105 watts power limit for ETH. I assume you are burning at least 150 watts on ZEC, right?
Claiming ZEC is more profitable than ETH shows lack of understanding....
There are tax implications with buying and selling as well though. Mine a coin hold long term and should be taxed at a different rate if you mine one coin, insta sell it for another. Some people dont like using exchanges, etc.