After using the same font for everything, I recently fell in love with this absolutely beautiful and extremely readable font.
For years and years I've been using a terminal font that I modified to add support for ASCII-art and some Menlo Powerline glyphs. I was quite satisfied with the font, but over the last few years I've noticed that my eyesight isn't what it once was, and I've had more trouble reading the font and having to zoom things in more often. Also, the ASCII-art got screwed up at a few font sizes. Finally I simply have had a feeling lately that the font didn't "pop" as much as it once did. (I cannot for the life of me remember what font I based it on, and I guess it really doesn't matter).
The other day while watching an Emacs tutorial on YouTube, my jaw dropped. The font used by the author of the video looked, in my honest opinion, stunning. And, at least for me, was extremely readable compared to anything I've used before, even when very small.
Not only is this font good looking and readable, but it's also very impressive. The font is actively developed. It has an insane amount of glyphs available, and more are being added. It comes in many different varieties, and each variety has a full range of variants. Everything is available as TTC, TTF and webfonts. It even has an online customization tool that allows you to generate fonts with only the exact variants, glyphs and varieties you need. To see every glyph available in every variety and variant, there is a specimen tool.
This is now my default font for more or less everything I do, and I highly recommend checking it out, and testing it your self.