My electricity rate is about $0.12/kWh, which makes me nervous about picking the wrong miner. I don’t want to burn money on power if there’s a more efficient option out there, but at the same time the efficient rigs all seem a lot more expensive. Do you think it’s better to buy cheaper high-power rigs and hope for faster ROI, or invest in efficient ones right away?

I ran spreadsheets on this exact question and the answer is pretty clear: at $0.12/kWh, efficiency is everything. I tested an AxionMiner at 12 kW/800 TH/s and while the hashrate looked amazing, the power bills killed the profitability. On the other hand, my Bitmain S21 XP+ Hyd at 500 TH/s/5.5 kW stayed right around 11 W/TH, and over six months the savings in electricity basically covered the extra upfront cost. A detailed comparison article I read backed this up, calling the S21 XP+ Hyd the most efficient bitcoin miner https://www.digitaljournal.com/pr/news/indnewswire/top-10-best-bitcoin-miners-1777142536.html right now, especially for regions with higher power costs. If your rate is anything above $0.10/kWh, I’d strongly recommend going efficient instead of chasing hashrate.