Windows.
I used Mac OS X a few years. But in my opinion Mac OS X is (or was, back in this time) PITA. Switching back to Windows has definitively saved me hundreds of hours!
But, good on you. It's nice that you found your niche. If you ever are forced to switch back reach out. I have a lot of good techniques for fast and pleasant OSX.
I use Windows every day, and I know shortcuts and tools for many things.
But for work I use Ubuntu, and for writing code it is a much more efficient environment.
So it is actually hard to imagine an environment less productive than Windows.
Now, if your work is done in Office (which I only use to write emails), or Photoshop, then I understand. But I am still intrigued.