Glad to hear that I was able to contribute 🙂 ! And thank you for your great reply!

I prefer KDE over gnome (I think that’s what’s bothering me about my install of popos at the moment)

That could definitely be it. No worries, even the community is somewhat polarized on GNOME; with a big chunk of the community favoring it over all the other desktop environments, while another big chunk doesn't tolerate it at all. However, the reason that everyone has an outspoken opinion on it comes primarily from the fact that a lot of distros come with GNOME by default; with both Ubuntu and Fedora being the big ones (sure; both have flavors/spins with other desktop environments, but their main ISO defaults to GNOME). Regarding recommendations; while any major (independent) distro should technically suffice, I would argue that Kubuntu and openSUSE (contrary to the others; openSUSE actually defaults to KDE) are both excellent choices, with both Fedora's KDE Spin and Debian (on which you can pick KDE during first install) are very good choices as well if you lean more towards minimalism. While Arch deserves a mention regardless, I don't think you're ready (yet).

Typing command line doesn’t bother me (on the opposite: I feel like I understand what is going on better if I can actually type in commands)

That's great to hear!

but I don’t fully understand the difference and advantages/disadvantages between pacman, apt, yum, etc. I’m more used to apt and I feel like there’s more information available, but that’s it.

I won't be able to be exhaustive on this, so I instead I'll lean more towards being somewhat oversimplistic for the sake of brevity.

• pacman is the package manager on Arch(-based distros)
• apt is the package manager on Debian(-based distros)
• yum used to be the package manager on Fedora(-based distros), but has since been replaced by dnf. You can still install packages using yum on these distros, however it's just an alias for dnf.

These are not the only package managers out there, as almost all independent distros come with their own package manager; apk (on Alpine), eopkg (on Solus), xbps (on Void) and zypper (on openSUSE) etc. The tasks of the package manager are varied, but all of them are to be interacted with when installing, upgrading and removing software. As the feature-set is different, so too are their performances. A rolling release distro like Arch will receive a constant stream of updates, thus having access to a package manager that's very fast is beneficial. Thus we find that pacman is very optimized for speed. To perhaps illustrate how much difference this can make, I compared Alpine's apk with openSUSE's zypper. Note that Alpine is one of the most minimalist distros out there, and its apk might be the fastest package manager that's in active use. So here are the results:

• sudo apk add firefox 0.01s user 0.02s system 0% cpu 8.216 total
• sudo zypper install -y firefox 0.02s user 0.06s system 0% cpu 33.727 total

On which the number before total reveals how much time it took in seconds. These tests were done in distrobox containers btw*.

Speed is not the only important metric, however as ultimately one can not engage with packages without waiting for them to be installed/updated/removed, a lot of the discourse is about how fast the package managers are at installing, updating and removing packages.