This is where you will find information about the most energy efficient mining hardware recommended by @phusionphil or any of the Phusion's Multipool affiliates.
ZEC
Zcash
Nvidia ~ ASUS ROG STRIX-GTX 1080ti 11GB 352-Bit GDDR5X
http://www.newegg.ca/Product/Product.aspx?Item=14-126-186
**750 Sol/s @ 200 Watts**
XMR
Monero
AMD ~ Radeon RX Vega 56 8GB 2048-Bit HBM2
http://www.newegg.ca/Product/Product.aspx?Item=14-932-001
**2000 sol/s @ 200 Watts**