A list of monospace typefaces I've found that support polytonic Greek without ugly subsitution of characters with diacritical marks. Most fonts can be found at the Codeface Font Archive. Fonts I use (or have used) are in bold.
- Hack
- Terminus
- Fira Code Light
- Oxygen Mono
- Office Code Pro
- M+ 2m
- MonospaceTypewriter
- monoOne
- Metrickal
- Meslo LG M DZ
- Mensch
- Liberation Mono
- Linux Libertine Mono
- Luxi Mono
- Luculent
- Lekton
- Iosevka (Slab)
- Inconsolata
- FreeMono
- Cutive Mono
- Cousine
- Courier Prime Code
- CMU Typewriter Text
- CamingoCode
- Bront
- AverageMono
- Aurulent Sans Mono
- Agave
- Whois mono
- Verily Serif Mono
- Ubuntu Mono
- Share-TechMonoTrue
- saxMono
- PT Mono