I downloaded Windows 10 on my main computer to keep up to date, but still have it on my old laptop. Knowing both worlds, I'd love Windows 7 to stay as the main version.
The main reason? Whenever I have a problem on 10, I keep finding step by step solutions that work, but sometimes it tells me to a certain window in a given fashion, but I don't see that on my screen or it doesn't open the same screen as in the guide.
Windows 7 help guides have always been on point for me. Also the interface is a good example of LESS IS MORE. I don't need all those little Windows on my start screen with News, my health, Minecraft, and other sponsored content.