But there comes another problem: some fonts look better with specific rendering options than others, in other words, when you change fonts, you often have to adapt the rendering options as well. Depends on the info provided by the ttf/otf fonts.
I still haven’t managed to find an easy way to have different screens with different DPI. I have two monitors (24"@1920x1200, 27"@2560x1440) and one TV (40"@1920x1080) connected to my graphics card, and obviously the DPI varies greatly, so I had to find a compromise.
Just for the record, here are excerpts of my config files regarding fonts:
~/.gtkrc-2.0 and ~/.config/gtk-3.0/settings.ini:
With these settings, the fonts (Oxygen as main font, terminus in urxvt terminals) look great for my eye.
Here’s a screenshot (i3), hope you see the fonts sufficiently well. On the right, you see the listing of links in /etc/fonts/conf.d. In the middle, rofi dmenu using Roboto Slab font.