I've appreciated endeavourOS's installer and defaults. It's Arch-based and has an option to install KDE/Plasma as the default desktop environment. I only back up my home directory, but I'm sure there's systemwide options, like btrfs snapshots (although that's a whole thing you'd need to test/verify). It's not an immutable distro. And, being Arch-based, it gets frequent updates. I've had a handful of issues from a package being too cutting-edge, but often it gets resolved within a few days at most with an update. Never had something totally break my system that I didn't cause myself (mostly symlink traversal). Just read up on pacman's flags (particularly -R flags, like -dd, -s, -n).