Arch Linux. Everyone said it was hard to use, unstable, etc. but my experience with it has been the exact opposite.
Yes, the install process is needlessly complicated (although it got a lot simpler now that we have archinstall), but the OS itself is rock solid and rarely has any issues that require more than a reboot or a package reinstall to solve. The AUR is a godsend too if you don’t want or don’t know how to compile stuff from source.
I’d say I’m a “time-strapped” user since I have a full time job and I’d rather spend my free time gaming rather than fixing a broken OS, nevertheless… I have 2 PCs with Arch Linux (one for personal stuff and one for work) and a server with NixOS.
When things break on Arch (which is rare these days but it can happen, especially if you play around with things from the AUR), I just rollback with timeshift (it takes just a few seconds with btrfs) and try that update again in a few days. Minor issues I can just ignore or work around them and take care of them when I feel like it, but they usually get fixed with updates within a few days. The only time I felt that it was actively wasting my time was when Plasma 6 came out a few months ago and a lot of little things broke, especially on wayland, but they were fixed rather quickly with 6.1 so I can’t complain too much.
NixOS on the other end has been nothing but trouble and a waste of time ever since I installed it. It took me a week to configure it, some packages are kinda old, most have incomplete declarative config, I had to manually write some units myself, and when things break it drives me crazy because even basic troubleshooting of services can be a pain in the ass because I have to find out where stuff is, know which config files are going to be overwritten, launch the correct nix-shell, … it’s all so tiresome… so I just revert to an older config and hope for the best. To make things worse, major updates often require manual changes to the config or even to application files themselves (looking at you, nextcloud) and you will excuse me if I can’t be bothered to do that on a DECLARATIVE DISTRO. Even debian doesn’t need that, come on! I don’t care what people say on NixOS, this OS is not ready yet, I don’t have time for this shit when I’m working and that server will be going back to debian next summer.