It’s often a laptop, something us nerds wouldn’t buy generally speaking, so they tend to have hardware issues. So newer tends to be better. So plain old Fedora workstation with gnome. I pin their favorite programs to the dock, and show them the basics of the interface. I show them the software button and say they can install anything they want from there, and that they should do the updates that pop up from there.
Zero issues. Honestly does a better job than windows - things are more intuitive for the non tech savvy.
Edit: mint is pretty good too if it works. It’s one of those two systems.