I asked the same question a while ago and decided to settle on Arch as container.
Why?
Pacman is extremely fast. I used a Fedora-container a while too and it was extremely slow compared to Arch
Simple syntax, especially with the Arch plugin for zsh.
Minimalist
Official packages are (almost) just as secure as from other distros
I get the newest stuff
Good documentation
The AUR. I rarely need to use it (pretty much never), but if I would need to, it’s great I can.
I still rarely use it. I’m leaning more to the casual user side and use Flatpak 99% of the time. But for terminal use, I find the said container, with zsh + plugins great. There are some programs (Nextcloud client for example) that don’t work 100% with Flatpaks, and for that, the Arch packages are actually pretty reliable and work almost every time (via distrobox-export).
I had a few doubts about Arch, and I personally still wouldn’t use it as distro for everyday use, but at least as container, it’s elegant and lovely. I could use Silverblue as unbreakable base and install everything with Arch, and nothing breaks.