Personally, I think that Apple should work on a unified operating system and discontinue the development of iOS (The new iPad PRO is an attempt of giving continuity to iOS). iOS doesn't work for professionals like developers or photographers. It's a very limited operating system, within which everything has to be controlled by Apple, in order to publish software.
OSX, however, it's an awesome operating system, although it's lately differing too much from POSIX. In my opinion, it just needs a new responsive and mobile oriented face (and of course, this is a big work). I believe they should work on the operating system that will replace them all, like Microsoft has been doing Windows 10. This would let us finally use real photoshop or development tools in our iPad.
Anyway, I like Apple products and I found myself very comfortable using the latest version of OSX El Capitan. Although I did not have high expectations, there is a feature I use everyday and makes me very happy :).
The new Split View for fullscreen applications is quite handy for developers. You could have a terminal in one side and your favorite IDE on the other side. Or you could have your IDE and you browser. This is my currently preferred development environment.
To change the focus between split panes, I use the custom OSX shortcut
option + backtick:
This became a very comfortable environment for development purposes.