Asklemmy

L4! Imagine all we could do if the kernel was tiny and everything was user space.

Yeah, I was going to say Haiku. It's surprisingly capable for this day and age (although needs tonnnns of work)

Firefox OS. ...really I just want Chrome OS but FOSS by Mozilla. I know it's anti-privacy, but having sign-in + 1 click deployment on a new device is dope

Redox OS seems like it's turning into something cool.

To name something that hasn't been mentioned yet, ArcaOS, which based on OS/2. It supports modern hardware and in addition to some preinstalled software, it also has some compatibility layers to run software from other OSs.

The only one of these that I know is Haiku (as an extension of BeOS). I was already a Mac user when Apple was flirting with purchasing Be, so I installed in on my PowerMac 9500 and took it for a test spin. I liked it, though I was too young and inexperienced (and this was pre-broadband) to really get a good feel for it. I think I switched back to MacOS within a day just because what else did I know to do with it.

Refox OS. I know today isnt a magic bullet but it makes committing memory mistakes a lot harder. Also rust gets first class status as the is standard library calls it and we can slowly get over the legacy of C.

Something with a microkernel.

Or ideally, something like Android was supposed to be, with exclusively non-native executables. "Java but good." So I guess some .NET atrocity, or an obscure SPIR-V project.

PalmOS as an alternative to Android/ios

Qubes

OS/2 Warp

Haiku - based on BeOS

"inspired by" would be more accurate. there's no original BeOS code in Haiku for legal reasons (other than the interface, which was open-sourced with the release of BeOS 5). All backwards-compatibility with original BeOS software is (impressively) reverse-engineered. Haiku OS is, itself, original software made to - in every way - look, feel, and operate just like BeOS did.

edit: i had a buddy in high school who had a BeBox. it was like having the best of a Mac and a PC in one machine. it really was a spectacular machine and OS. i really wish Apple had picked it up, but they went with NeXTSTEP instead, which, i admit, was still a pretty solid choice.

Qubes

Serenity is beautiful, so I guess I would pick that.

Plan 9

It is an absolutely revolutionary OS by some of the original creators of Unix, that extends its core concepts in more coherent and elegant ways into the world of modern computing, instead of having everything from networking on up be tacked on by people who were perfectly capable but lacked the vision.

Examples:

Instead of NAT, if one machine on your network has the internet and the others don’t, you can say “use that other machine’s network stack now” and boom everything works. Your machine knows what its real external IP address is, it can listen on world-facing ports on the other machine as it needs to, everything works and is simple.

There’s a command for “run the rest of this session’s commands on that other machine’s CPU / memory” and it all just works. The sensation is that your computer just got magically faster.

Etc etc. I actually haven’t played with it extensively, and deployment is so limited that I’m not sure how useful it would even be, but if you are a fan of well made OSs that do things in a genuinely different fashion, it is objectively the best option to play around with. sdf.org has a place you can get an account on their Plan 9 machines and they do little free beginner courses in it over livestream.

HURD, obviously.

I'm happy with any OS as long as it's GNU.

I'd love for FreeBSD to become more mainstream/popular (again)

MorphOS. It's still kicking.

ReactOS. The "We have Windows at home" OS.

Maybe then it will see proper development to become that which it should be.

TempleOS

Haiku is already pretty great to use in my opinion, despite still being in beta; with the right hardware you could easily daily drive it