A windows PC for gaming
A macbook for my laptop
An Arch Linux PC/Server that I use for most of my work and that hosts all my services
The "why" for each is probably pretty self-explanatory for each. I'm a firm believer in using the right tool for a given job, and I think Windows has the best gaming experience, Mac has the "best" laptops (for my own subjective value of "best"), and linux is the best for software development and service hosting.
In a perfect world I'd use linux for all 3, but while gaming on linux has gotten a lot better, it's not quite "there" yet, and I just love the new Apple chips for laptops in terms of battery life, speed, and heat management