When it comes to triple A games or the vast majority of mainstream video games in general, Mac is not the best option. Playing on PC gives you access to adult games on Steam, but also to all of Nutaku free porn games and to the crazy amount of indie sex games you can find on Itch.io, meaning you'll have to live another 9 lives if you ever want to play every great +18 game out there! Mac is also great for free adult games
Unlike consoles, adult games don't have exclusivity and developers are trying to develop their games for as many platforms as they can, starting with Windows. If you're looking for free porn games and sex games in general, playing PC is by far the best choice. Play free porn games on PC, Mac, Android, iOS or Linux PC is the best platform for porn games