For a long time, I’ve just put on DejaVu fonts and been done with it. Generally good enough Unicode coverage for me. But I know it’s been years since DejaVu’s been updated, and I wonder what’s very common today.
[As for the terminal, I’m guessing it’s usually still the standard fixed Unicode fonts?]
Lots of great fonts and families mentioned so far in this thread, but no-one has mentioned my current and long-time favourite for almost all environments and applications: Input.
$ echo sans serif monospace | xargs -n 1 fc-match InputSansCondensed-Regular.ttf: "Input Sans Condensed" "Regular" InputSerifCondensed-Regular.ttf: "Input Serif Condensed" "Regular" InputMono-Regular.ttf: "Input Mono" "Regular"