Just wondering which distro you would you go for if you are the one having to provide support over the phone or in person.  I am assuming that the person just wants to browse the web, watch youtubes, go on facebook, print out the odd document,  & so on.

I was thinking Ubuntu, Mint, maybe Xubuntu.  (I've looked at MX 17.1 and although the reviewers love it, & say it would be great for beginners, I tend to think that there is an awful lot to tinker with!)

I'd say Ubuntu 16.04.x with Unity might be hard to beat - it's still got at least a couple of years of security updates to go.