The Linux, GNU/Linux, and BSD ecosystem in general. Since most applications are portable between distributions, an improvement made by one vendor will eventually propagate through everything. A new feature in KDE Plasma will appear both in EndeavourOS and Kubuntu. A security fix in OpenSSH (which is maintained by OpenBSD) will appear in literally all distributions and even Windows.
(edit) This obviously doesn’t include technically Linux/BSD systems like MacOS and Android. Their existence is sacrilege, and while they are on the council, we do not grant them the rank of Linux or BSD distribution.
Loops needs a dark mode and it needs to be on by default. That was legitimately painful to open in the dark.