99 percent of the time, I'm running OS X. But, I do keep a dual boot (OS X / Linux) Mac Mini handy for the odd cases where a particular program happens to only be available for Linux, or if I experience strange behavior from an application hosted on OS X.
For example, I was getting system crashes after upgrading my Macbook Pro (mid 2009 model) to Yosemite, and running Arduino IDE. Attempts to upload sketches to the target Arduino would make the entire operating system crash. Very dramatic. Thankfully, this problem hasn't appeared when using my new iMac.
I was a hard-core Linux desktop user for over a decade. Still do a lot with that operating system on the server side. But, as soon as I could afford to do so, I bought a Mac. I love not spending unscheduled time fiddling with the operating system when I have serious deadlines to hit.
Recently I bought a Lenovo Yoga 2 for a very rare bit of Windows IE testing for a web app. As soon as that activity concluded, I ditched Windows 8. Linux Mint is a delight to use on it.