SSH in first place. No explanation needed.

But also MATE and Pulseaudio (yes). I really like paprefs, pasystray, and how easy it is to send audio over the network. To the point where I reinstall Pulseaudio instead of Pipewire, because Pipewire requires long command lines for what was easily done in a few clicks with Pulseaudio.

I dread the day where I will be forced to "progress" to Pipewire and lose that easy feature.