My own preferred .fonts.conf.

.fonts.conf

<?xml version="1.0"?>                                 
<!DOCTYPE fontconfig SYSTEM "fonts.dtd">
<!-- ~/.fonts.conf for per-user font configuration -->
<fontconfig>
  <alias binding="strong">
    <family>sans</family>
    <prefer>
      <family>Ubuntu</family>
      <family>AR PL UMing TW</family>
      <family>Noto Sans T Chinese</family>
      <family>Noto Sans Japanese</family>
      <family>Noto Sans S Chinese</family>
      <family>Droid Sans</family>
      <family>Droid Sans Japanese</family>
      <family>Droid Sans Fallback</family>
      <family>MOESongUN</family>
      <family>TW-Sung</family>
    </prefer>
  </alias>
  <alias binding="strong">
    <family>serif</family>
    <prefer>
      <family>Ubuntu Light</family>
      <family>AR PL UMing TW</family>
      <family>Noto Sans T Chinese</family>
      <family>Noto Sans Japanese</family>
      <family>Noto Sans S Chinese</family>
      <family>Droid Serif</family>
<!--      <family>Droid Sans Japanese</family>-->
      <family>Droid Sans Fallback</family>
<!--      <family>MOESongUN</family>-->
<!--      <family>TW-Sung</family>-->
    </prefer>
  </alias>
  <alias binding="strong">
    <family>sans-serif</family>
    <prefer>
      <family>Ubuntu</family>
      <family>AR PL UMing TW</family>
      <family>Noto Sans T Chinese</family>
      <family>Noto Sans Japanese</family>
      <family>Noto Sans S Chinese</family>
      <family>Droid Sans</family>
<!--      <family>Droid Sans Japanese</family>-->
      <family>Droid Sans Fallback</family>
<!--      <family>MOESongUN</family>-->
<!--      <family>TW-Sung</family>-->
    </prefer>
  </alias>
  <alias binding="strong">
    <family>monospace</family>
    <prefer>
      <family>Ubuntu Mono</family>
      <family>AR PL UMing TW</family>
      <family>Noto Sans T Chinese</family>
      <family>Noto Sans Japanese</family>
      <family>Noto Sans S Chinese</family>
      <family>Droid Sans Mono</family>
<!--      <family>Droid Sans Japanese</family>-->
      <family>Droid Sans Fallback</family>
<!--      <family>MOESongUN</family>-->
<!--      <family>TW-Sung</family>-->
     </prefer>
  </alias>
  <alias binding="strong">
    <family>Terminus</family>
    <prefer>
      <family>Terminus</family>
      <family>AR PL UMing TW</family>
      <family>Noto Sans T Chinese</family>
      <family>Noto Sans Japanese</family>
      <family>Noto Sans S Chinese</family>
<!--      <family>Droid Sans Japanese</family>-->
      <family>Droid Sans Fallback</family>
<!--      <family>MOESongUN</family>-->
<!--      <family>TW-Sung</family>-->
    </prefer>
  </alias>
</fontconfig>