Arch Linux or Artix Linux. Will write about them soon...
I highly recommend suckless's dwm, because it is extremely lightweight, fast and highly customizable. The are several drawbacks such as lack of documentation and patches (you usually have to install patches manually by editing the code).
st(simple terminal) - suckless terminal. St supports UTF-8 characters, emojis(install libxft-bgra). I personally use Luke Smith's build of st. Will probably make my own soon.
Neovim and vim can improve your productivity.
Firefox is an open-source web browser. You can extend it with some extensions:
mpv is a lightweight, open-source, and reliable media player. You can play YouTube and other internet videos using mpv simply by installing youtube-dl.
cmus is a lightweight music player with vim key bindings.