Windows 10 or Windows 7?
BEST OPERATIVE SYSTEM FOR GAMING
I think 10 is better
10 hands down. The entire O.S. was constructed with gaming in mind.
Windows 10 is newer and it will have longer support.
10 = future focused
7 is really good but I prefer 10
Windows 10, you can also google god mode and create a desktop shortcut that allows you to access all the features of windows 10 in a single click. You can also use compatability mode for everything. The only downside is Cortana. I haven't been able to disable that.
I liked Win7 more, but as Win10 is better and will have longer support, one needs to switch sooner or later. Some of my computers have 10, some still 7.