It's all about Mac OS. It lets me get things done without dealing with silly things.
Let's quickly list what I sorely miss when switching to my Linux machine:
* Multiple monitor support: connect any number of monitors, any time, and have them Just Work. HiDPI or not, doesn't matter. The OS even remembers which of your windows where placed on which monitor at which size, and will do its best to move them when you connect a monitor. No other OS even comes close.
* Consistent keybindings (Emacs-style) in all windows and dialogs. Control-a always gets me to the beginning of the line, whether in a text editor or in a file-open dialog box.
* Reasonably consistent keybindings in apps. Can expect Cmd-q to quit every app.
* Flawlessly working suspend/resume on laptops.
* Full-screen any app and it works fine.
* Apps like LaunchBar (I think quicksilver used to be a free alternative).
* Spotlight, which finds everything.
* Ability to remap any key to whatever I want and have it work everywhere.
* Drag & drop everywhere. And if you laugh at this, consider that this is coming from a command-line guy with 25 years experience with computers. The way Mac does drag & drop is faster and more convenient than fiddling with command line. For example, did you know you can drop a file or a directory from anywhere into any file/open dialog box?
* Apps like Simplenote, Bear, Ulysses: excellent tools for specific purposes.
* TextExpander.
* Predictable ubuquitous working clipboard.
For me, switching over to my Ubuntu machine is an exercise in frustration. I can't redefine my keys, there is nothing like TextExpander, multiple monitors just don't work unless stars align just right and you have all the monitors in just the right order at boot time and you better not mix hidpi with normal. Drag and drop is nonexisting. Copy/paste is a free-for-all where each app does things differently and you have multiple clipboards (Ctrl-V vs middle mouse click).
Basically, in order to get things done, I'd much rather work on a Mac.
A side note: to really understand why the Mac is so good, you have to work on it for a while, with someone showing you things (like dragging files into file/open dialogs). People seem to think this is about superficial things like aesthetics, or Adobe software. It's not.