+1 for Fedora KDE. I’ve been daily driving it for 2 years now and its given me very little problems. I stopped using Windows about 5 years ago now and haven’t looked back, and after distro hopping for a bit, I’m pretty satisfied with my experience with Fedora. Initial setup can take a little bit because theres some repos you need to add/enable to get nonfree software (including video/audio codecs that basically every website ever uses), but once you do that its pretty solid. You get pretty up-to-date software without it being so new that things break after every other update. It strikes a nice balance.
However, if you’re familiar and comfortable with Ubuntu, you’ll likely be just fine sticking with that. You probably won’t notice huge performance differences between distros. It sounds like the bigger concern is if you’re safe to just nuke Windows and I’m not going to be the one to discourage you from doing that. Up to you if you want to try something new or not.
I think it’s more about making sure you can handle yourself under pressure. When there’s multiple guys actively beating the shit out of you, can you still focus on naming the cereals? Or does panic take over and your brain stops working after you only have a chance to name 3? I guess it makes sense that a group of domestic terrorists would want someone that can keep their head on straight when shit hits the fan. Still dumb tho.