Plain old Fedora.
I know the hurdles, i know what to expect, and I've never been surprised by it.
Immutable sounds nice, AUR sounds nice, NixOS sounds nice, but i am utterly confident in my current choice's reliability and comfortable with its idiosyncracies. Everything i want to do works very well.
If i had less time/energy or had to switch, Kubuntu would be my second choice. Less frequent updates and fewer creature comforts, but also very reliable.