Abstract: Use Linux Mint.

Welcome to the Linux community! I say that so often I've bound it to an autokey macro, I run it for every newcomer I greet.

First bit of advice: Don't wait until Windows 10 is unsupported and you're FORCED to a new OS to start learning Linux. Simple reason: Linux is a very different system. There will be culture shocks. An example I cite a lot is Linux doesn't call them "shortcuts." What Windows calls Shortcuts, Linux calls Links or Launchers, depending on exactly what it does. A shortcut to a document is a Link, a shortcut to a program is a Launcher. Makes perfect sense...and is different than Windows. And those culture shocks will spend months throwing you around.

I switched to Linux because I HATED Windows 8.1...and I kept a copy of Win 8.1 on that computer for that wretched products' entire lifespan. In case I found something I didn't know how to do in Linux. There were times when I had...let's say an essay or something I had to turn in on a deadline, and this required a task that I knew how to do in Windows, but that's not how Linux works...I found it best to just do it in Windows, turn it in, then when I had plenty of time and no pressure, I could easily learn how to do it later. Eventually that kind of stopped, and then reversed. Nowadays Windows feels foreign to me and Linux feels like home.

I also suggest starting to use FOSS software applications like LibreOffice as soon as you can, because honestly the OS isn't the thing that causes the real problems, it's the software library.

As for which distro: It honestly doesn't matter all that much, They honestly have more in common than they have differences. The major component that you'll really feel the difference in at first is the desktop environment, and that's a personal and kind of visceral choice. There are people that absolutely adore GNOME. I absolutely despise it; this is no hyperbole, if given a choice between using GNOME and using no GUI at all just the terminal, I'm using the terminal. A lot of people really like KDE. I can't put my finger on why, but KDE feels dead to me. There's some uncanny vacant quality to KDE, it gives me the same feeling as a website that is still on the internet but hasn't been updated since 2006. Cinnamon feels like home to me, I'm very comfortable with it, other people can't stand it for reasons I don't comprehend.

This is why we have choices.

I do generally steer folks away from distros that are, basically "Forks of Kubuntu with our own non-specific special sauce that makes it good for [beginners/gamers/trout/Anglicans/veterans of the Falklands war/cellists/hackers]." Because their own special sauce is going to be a skin for the settings menu that's 10% jankier, and a different color scheme. I would stick to top level distros like Debian or Red Hat, MAJOR forks like Ubuntu or Fedora (though Ubuntu is going so corporate these days I actually try to steer folks away) or DE flagship distros like Mint, Pop!_OS or Neon.

This is my tenth year of using Linux Mint. It stands the test of time, it doesn't Just Break the way the memetastic rolling release distros do, the GUI feels complete but not bloated, and...to me it's home.