I just love the integration. Everything looks nice (yes I even like Yosemite), the system is very stable, I can go days without so much as a restart, it doesn't break after I install a package from a package manager, the upgrade process is seamless, the hardware is second to none (even Linus Torvalds agrees), and I can always get help from the Apple Store if something goes wrong. Some of these things you can get with Windows/Linux, you can actually get pretty close, but you never seem to get them all.
The hardware and software integration on Linux seems to be really iffy, even if you get Linux to dual boot on OS X. The hardware support isn't there unless you compile your own kernel, which you have to get (if it's a newer system) an unstable version of, the touchpad gesture support isn't as nice, the whole OS doesn't look as nice as OS X, and you miss out on the integration between iOS, which is really important to me, at least. OS X is a proper Unix system, so any Linux command line tool will also run on OS X. And you actually get the basic tools out of the box (vim, ruby, python, zsh, tmux, perl, etc, etc). If not, you can get a really good package manager in the form of homebrew, and while it's not as powerful as apt-get, it's pretty much all I want from a system package manager.
I am also not a big fan of managing windows or using a tiling window manager, I don't even use them when I'm on Linux. I actually prefer using OS X's default Mission Control/Expose behavior (I know.). I toyed around with Moom, Slate (https://github.com/jigish/slate) but gave it up. I don't like windows to snap, that's an absolute asinine behavior that seems to be the default on Linux desktops these days, that I always have to unset. I never knew why anyone would be a fan of it, unfortunately, most people are. I just have my terminal run tmux and live there. Command+Tab is enough for me.
That all said (sorry if the above turned out to be a bit of a rant), Linux desktop environments are slowly getting much better, I'm really liking the look of Plasma and Gnome 3 (although that huge chrome, seriously?), and Elementary OS is easily the best Linux distro I've used.