OS X is pretty slick, but I have (for the most part) returned to the fold of Free Software. Nobody will remember when one of the political factions in the Philippine Islands scattered metal spike balls around on the streets of Manila along a parade route, to flatten tires. This was an incident where general harm was done to make a point against a specific faction or perhaps the state of the system.
OS X. Apple has scattered little spike balls around to prevent cooperation from taking place, and rewriting hallowed Unix / GNU/Linux tools to disallow cooperation.
Emacs: of the several versions I have not been able to sort them out.
I have to say, though, that in OS X's any differences between shell keybindings and emacs keybindings have been pretty well resolved, far better than in GNU/Linux distros I have used. I can setup for emacs keybindings in Gnome or XFCE, but some of the bindings (Ctrl-K) do not work. How emacs works is more important to me than any window manager shortcuts. I call them emacs keybindings, but I think there is more to it than this. ARe these actually original bindings from Unix?
OS X has some brilliance, but I am disappointed in the hardware. SD cards are a mess, and the slot is inconveniently placed in my 27" iMac. In fact, their configuration leads the sd card to scrape against the rough aluminum edges. Several USB flash drives are not working well with OS X. Linux smoothly allows me to read them and write to them even when not properly unmounted. This is software though.