Oh no look out it's the internet decency police! Seriously, think about the kind of answer the OP is looking for. Obviously he doesn't want Linux or OS X because they don't support most games.
I really hate Microsoft as well and would rather avoid supporting them if possible. Microsoft doesn't really need my money anyway considering BIll Gates is (or was?) the richest man in the world. You don't have to buy a license to use Windows 10. If you can obtain an ISO you can use it all you want just without the ability to change certain cosmetic features (you CAN still change the wallpaper by right clicking an image and clicking set to desktop background).
You might need a product key to download an ISO from the Microsoft website. In that case, just Google "Windows 10 generic product key".