I see them both as tools nowadays, and I use each for whatever it does best, so that I don't have to waste my time trying to do something on an OS that doesn't do it well. I game on Windows because it's flawless and I work on Linux whenever I don't need Photoshop. Whatever helps me do work faster.

On the desktop environment side I currently use Gnome simply because it's the default and I don't want to spend any time switching right now, because I don't really have enough of it. But I agree. A while ago I used XFCE and even I3 on my old computer and it made things run much faster simply because nothing else, except the things that I needed, was using the resources of my PC.