Windows 7 is definitely the best for gaming, however if your system comes with 8.1 pre-installed, then Windows 10 is definitely the way to go. The reason 7 is great is because it's not about good looks, it's about performance and straight-forward processing. Meanwhile, Windows 8 and 10 are more about appearance, and they both lack the default capacity for gaming. However, the reason you should leave Windows 8, is due to the Xbox features that Windows 10 has. Anytime you game, you can stream it, record it, and share it, just as you can on an Xbox One. My opinion? Stick with Windows 7 if you have it, but last resort is Windows 10.