sp20 jackson vs Bitmain Antminer S7 for personal bitcoin mining
You are overlooking a very important part of the costs, that you already mentioned. The energy!

Roughly at 13.0 cents per Kw/h your yearly energy costs are:

Scenario one:

21 x 1.2Kw x 24h x 365d x $0.13 = $28697.76 USD! you are down quite a bit.

Scenario two:

6 x 1.293Kw x 24h x 365d x $0.13 = $8834.81 USD! you are down a bit less but still not enough..

So the only way you will make $$ its that BTC value raises in price, in which you are better off just buying off BTC right now for whatever value you are planning to spend.

You need to add into account that mining difficulty will rise and payouts will be even less.

Hopefully this brief info helps you decide (I was a miner myself 2 years ago)

Best of luck!