I've put together this blog post, which is a comprehensive, and occasionally still growing, comparison between Windows 7 and 10, concerning both general use and user experience, as well as it specifically relates to gaming:
Personally, I would keep Windows 7, because you lose a lot more with Windows 10 than you gain, including a loss of control, stability, and privacy. While Windows 10 has DX12 support, Windows 7 has Vulkan support, which accomplishes the same thing, to produce better performance in games that support the API.
You'll have to decide for yourself what trade-offs matter to you most.
