Fullscreen mode loses focus constantly with 2 monitors, SMB shares are very slow especially with large amounts of files to be listed. Finder crashes a lot dealing with network filesystems. The search on Finder is extremely bad and doesn't hold a candle to Windows 10 search.

I am typing this on a Macbook Pro so I am not some Windows fan. OS X has fallen way behind in its desktop incarnation. The only reason I use OS X is due to its Unix shell for development. I don't think anyone can honestly say that as a GUI OS X is better than recent Windows.