Since there are many hardware now out there for sale, the best one should be chosen by a performance index. The best index is efficiency which is :
Efficiency= (Hash Rate)/ (Power Consumption)
Some people chose their mining hardware only by looking at the its hash-rate which is too wrong!!! Since you are using electricity and generating bitcoin simultaneously then you should consider its power consumption as well. It’s an important factor.
Important: Even if you have free electricity you should still stick to the above index and care about the energy consumption of your mining machine! Why?!…
Because even in the case you access to very cheap or free electricity, you still have electrical energy capacity (i.e. 5 kW or 20 kW or whatever) from which you cannot draw much more ampere or current due to you electrical infrastructure limits! Therefore it’s better to put more efficient miners connected to your electrical grid rather than less efficient miners with more hashrates! So be careful!
Sticking to efficiency index for selecting your miners lead to more life span of your mining farm as they will be usable far longer period because of their high efficiency. To make it simple, the more efficiency you chose, the more life of your mining farm you reach and the less replacement you need! (As well as less cost in the long run!)
In the below table I have collected the necessary information regarding the current bitcoin mining hardware in the market:
—————————This table will be updated periodically on quora version: https://qr.ae/TUGzcl ————————
I hope my answer would have been useful.
Good luck!
