I would say that the best way is solar mining, but this is something difficult for most users, not only because of the high initial investment, but also because of technical difficulties. Anyway, I think it's just a matter of time before we can see companies able to assist users with this.
Solar mining is only suitable in tropical countries, if the countries that have 4 seasons is certainly difficult. Based on my experience, the weakness for solar mining is high maintenance cost. better use of electricity if the price of a maximum of 10 cents.
I disagree with you about the high maintance cost, but even so, it's absolutely not free. So it only make sense if you're thinking big (creating a big mining farm) or small (you're hobbyist, so you can do most of it yourself)