So there is a big bar for the typical person. Can they boot off an image and press ok. I know that sounds sarcastic but some folks just can’t handle do anything more than using the system that came with their device. I mean someone my age should be plenty use to installing a system but, well, you know. If they can’t handle installing a system and does not have someone who can do it for them (keeping in mind those sorts will view every hiccup as the fault of the person who did it for them). Then buying a mac with apple care is the best way to go. If they have an issue they can go to the genius bar or call support or whatever. If they can handle installing a system but not much else then I recommend zorin which is an out of the box linux distro based on ubuntu lts and uses gnome by default. The main thing here is that its about as stable as a linux system is going to get with ubuntu lts, then it comes with any software someone could reasonably expect it to have. so stuff for doing pretty much all office and audio video stuff along with a browser of course and a fair amount of other things like disc burner software and an rdp client and playonlinux allowing many windows thing to be run or installed with a right click. Lastly most downloadable software has a debian option which will work fine although they can find most things they need in the software center. then to it will look for updates and nag them to get them installed automatically.