I use Mac OS at work and Windows 7 at home. I've owned a dozen of Macs, but I prefer Windows. To me Mac OS is very overrated. While graphically Mac OS is more elegant, Windows provides better usability.
1. Simple example: resizing a window.
Mac OS: if a lower part of a window is below the edge of my screen I have to make extra clicks to move it up so I can access lower right corner. Also maximize button does not work as well on Mac.
Windows: any window can be resized from any side and any corner.
2. Another example: dual monitor setup.
Mac OS: if you move application window to a secondary monitor, your top menu remains on primary monitor. Very odd
3. Another example: you trying to login to OS and you Caps are Locked.
Windows will tell you right away: Mac OS won't
4. Windows Library folders. In a library, you can collect files of various sorts without moving them from the folder where they're stored; libraries can even collect files from different disks. It's easy to create these collections of whatever you'd like and pin them to the left-hand side of the window.
Mac OS can't do this.
5. Windows is more keyboard friendly offering more keyboard shortcuts.
and the list can go on 6, 7, 8... I don't like MS Office ribbon though.