Most of the top answers are good so I will emphasize something that others have mentioned as well, which is that one of the lovely things about Linux is that your GUI, your window manager or desktop environment (different things I know, don't @ me) is up to you.
My personal favorite is xfce, but obviously a lot of people like KDE, Cinnamon, and Mate (mah-tay). There's of course a whole world of options beyond those, when you're choosing a distribution, go to the distro's website, and look at the screenshots. If they have different versions for different desktop environments or window managers, look at all the screenshots. Try to pick one that has a look and layout that looks comfortable to you.
Also backup your home directory. And remember you can always distro hop.