It's just not set up the way I want, with things like focus follows mouse, and it's harder to customize than Linux with a good window manager. I also prefer how Linux package management works; that it's an integral part of the system rather than something bolted on. I do like the screen and keyboard on the Mac, with the exception of the lack of volume buttons.
I also like the open nature of Linux. It's fun to be able to look into the source code for pretty much anything.
I've tried to push myself to use various Linux distros (most recently Pop and Ubuntu), but I always end up back on MacOS.