It’s the most highly optimised software available for consumer computers. Much easier when you support a very limited set of devices which you have compete hardware control over.

It is UNIX so very similar to using Linux when you use a terminal.

The UI is very polished and very stable. MacOS has not changed how the UI works or feels in a long time, during which windows and Linux (gnome/kde) have changed a lot. Both becoming more like MacOS. macOS has changed a little mostly features and styling.

It has wide support, including support for priority programs that Linux does not. Apple appears and feels like they respect user privacy much better than Windows. You feel like you paid for the product and you are the customer. Unlike windows, where you pay to be exploited for data harvesting to the real customer advertisers. Apple is in many ways in between windows and Linux. Not as free and open, but not as exploitive and limited as windows. It’s a common misconception that MacOS is somehow locked down or walled off, it’s less locked down and walled off than windows. But like Linux it requires some terminal know how.