It’s a bit of an unpopular opinion, but if you pick a mainstream distro there isn’t a lot of difference between them. Especially to somebody who is new to linux.
With most any distro you can use KDE, gnome and other desktop environments. You can pick which one you want to use when you login. So don’t think you’re tying yourself to KDE if you install kubuntu or something.
If you want an easy way to switch to a new distro make sure you create a separate partition for /home. Then if/when you want to install something new you can have it overwrite everything except your home directory. So all your steam configs and games will be left untouched (for example). Alternatively just backup /home somewhere and restore as you need.