I spend most of my waking hours staring at text, either writing code or in a terminal. Before I made my living as a sysadmin, I spent years working in graphic design and publishing. I love typography, and I read text on screens all day, and I pay close attention to the typography I encounter1.
For many years, my monospaced font of choice was Inconsolata. It is an excellent typeface that I have used every single day for more than five years, but Hack has eeked it out as my new daily typeface. I find Hack to be slightly more legible than Inconsolata, though Hack Bold is a hair too heavy to my eyes.
Besides being pleasantly legible, Hack has an impressive collection of 1,500+ glpyhs, free CDN hosting, detailed instructions for self hosting, and an active open source project. I highly recommend you check it out.