Windows10, cause I'm a basic bitch. I've tried to run Linux a couple times years ago, but games not running properly and me not getting over the learning curve always got in the way.
You should give it another go now then. Gaming on Linux is very good nowadays with many games supporting the OS directly (even more now thanks to SteamDeck) and there are many ways to run even games that don't. Also, there is a lot of Linux distributions that are extremely easy to setup and maintain.