Linux

In my experience?

Mint has been around longer and has had more of the lumps smoothed out. Mint, and their flagship DE Cinnamon, has always been about actual usability. There's a pragmatic streak that runs through Mint that isn't there in some other distros.

It has been my experience that Mint is usually the one that "just works" and the one that "continues to just work." Cinnamon's UI strikes a balance between KDE's "ALL THE FEATURES! MAXIMUM CLUTTER!" approach and Gnome's "Nuance doesn't exist, implement as little functionality as possible so the window stays empty and beautiful" approach. You won't find yourself asking "why can't it do this?" the way you do with Gnome-based distros. You don't have to start installing extensions just to get things that were considered basic features twenty years ago. You aren't sent to the terminal particularly often, you can genuinely manage most of the system from the GUI.

I would also say that Cinnamon is going to be more familiar to a Windows user than Gnome. Trying to use Gnome the way Windows users are used to handling things, say by minimizing and maximizing windows, is deliberately a pain in the ass on Gnome, and has a tendency to make newcomers think "Man this shit is unusable." Cinnamon doesn't have that problem; it's still fun convincing people that I'm running Windows 9.