I like TailsOS, which is an amnesiac system that runs entirely in RAM and boots from a USB hard drive. The goal for the operating system is to be a safe operating system for people who are in compromising situations - from international reporters to survivors of domestic abuse, it is a way to highly reduce your ability to be tracked.

The downsides of amnesiac systems are obvious - without enabling the setting for permanent storage, effectively everything you do on the OS is lost every time. And if you do enable persistent memory, well, that's not exactly entirely safe if you are caught out.

What I like the OS for though is as someone who is not compromised or in a situation where I need these privacies (despite appreciating them), my usage of it makes it safer for others who are using it (since internet is through Tor), and I feel more comfortable using computers in the wild when needed, since I'm not logging in on the public operating system that will be used by everybody else.

Many people give these projects flack or diminish their values as a "daily driver", but I think often times forget the important aspects of them. They may not be a daily driver for you or I by nature of our needs, but they are certainly important daily drivers for others. In addition to that, supporting a project that helps people in compromised situations and becoming another node to bounce off of (again, Tor, not inherent to the usage of this OS) is a nice additional benefit.

Tl;DR amnesiac operating systems because they're simple, straightforward, and make you feel more like whitehat hackerman when you've done nothing at all.