I don’t get the people recommending Mint and Ubuntu or atomic distros, those are great for a beginner who just wants their system to work without having to be bothered, but I’m not sure you could find worse if your goal is to learn how your system works…

You need :

• Good documentation, so that could find answers when trying to understand something.
• A large community, so you can ask questions if you need to
• Configuration that’s easy to mess with
• Not a distro filling a very specialized niche (don’t go for one of the distros without systemd, unless you actually know what systemd is and have a reason for not wanting it)
• One of the “base” distros, rather than one that is based on another one with modifications (that will make it easier to understand if you don’t have to deal with what Mint added on top of Debian for ex)
• No weird shit that confuses you when you try to understand what is going on (“Why is my lsblk spammed by fake partitions?.. oh right Snaps”… “Wait why is that a Snap, I installed the package with apt?”)

So I’d say either Arch or Debian (or Debian testing, if you want Debian but with updates more often than once every century). Not sure about Fedora, I’m not familiar with it.

Arch is a great way to learn how your system works, if you know what you are getting into.

The documentation is very extensive and a lot of people use it, so when you do encounter a problem you can usually find the solution easily enough in the docs or in forums.

I’m also not sure that it’s inherently more challenging than other distros, a lot of stuff is pretty much the same no matter your distro, except that with Arch nothing gets in the way so personally I find it easier to understand.

And the reputation Arch has for breaking stuff during updates is either very overblown, or I’ve just had the most terrible luck and missed all of them. I’ve only seen one big breakage, the FUSE regression, which was pretty cool, and that was fixed almost immediately.

There’s also software availability to consider, and Arch is one of the distros with the most packages available (second one after NixOS I think).

Personally I regret having wasted several months on another distro because people kept saying that you absolutely shouldn’t start with Arch, and that if you wanted to try Arch you HAD to do it with a manual install (guess how well that went when I was fresh from Windows 😂 ). So I failed to manually install Arch for a month, then I spend three months on a random other distro before finally installing Arch with the archinstall script. I expected that it’d be insanely complicated and that I’d break everything in a few days but it’s been surprisingly straightforward. The challenging part is understanding how things work when the documentation presupposes prior knowledge that I don’t have. Now after over a year I’m familiar enough with Arch that I’ll try a manual install when I change hard drive and reinstall.