I am trying out some different fonts, as I think the Noto fonts are totally okay, but not perfect.
I am currently using Inter, licensed under an open font license that allows free distribution as long as its not sold as the product itself. It looks pretty great, material design-y and adaptive so it can be used for multiple types from a single file.
Emojis work the same as with Noto, they are black/white outlined, sharp but some weird font I dont know. This has to be an extra package as it was not affected by changing the font, old known problem.
For monospace code fonts I currently use Hack which is under the MIT License. It looks nice, but not really a huge difference. Its a single font, which doesnt bloat the system like Iosevka can do (when installing all variants).
I think changing the system fonts could be a great way to make plasma look more modern! Many apps follow the system font, and in FF and Thunderbird you can even make content use the same font, so the system looks different, new, interesting and I also think very modern!
I will attach screenshots.