I'm currently using a Mac for private stuff, used to use Linux for work stuff, currently forced to use Windows. My font rendereing ranking is MacOS > Linux > Windows.
I rate it macOS > Windows > Linux. iOS is pretty good too, mobile Windows wasn't. But I'm only experiencing Linux graphically on a rather old monitor or through a terminal emulator, and macOS and Windows on a nice monitor, so that probably skews my perception. I wonder how many people observe the three OS'es through the same (or very similar) monitors.