Windows annoys me in that you have to manually refresh everything in a window to show changes, whether it is connected filesharing sessions, DHCP leases or files in a folder.
Windows Explorer search/indexing is slow and primitive compared to spotlight.
Mac is much better at organising large numbers of files and give you preview with the spacebar, or coverflow and metatag data is searchabl/sortable in the Finder. Imagine if you were a photographer with thousands of similar images!
However, I think Windows 8.1 is much better than previous versions even though most seasoned Windows users don't like it.
I use both, but if I could only choose one and my employer is paying, it would be Mac OS X - but with my own money...Hmmm, £450 laptop vs. £999? Maybe I would plump for Windows 8.1 even though the hardware would be inferior and OS not so much to my taste, I would rather spend the extra £550 on something else.