One advantage with Windows 8 is price. You can buy a new full version of Windows 8.1 Home or Pro retail for the same price as the OEM versions of Windows 7.
The OEM version remains locked to the machine you installed it on: If you sell your Mac, you can transfer the windows licence to the person you sell it to, but you can't keep it and reinstall it on a new computer. With Windows 8, you can sell it with the machine or transfer it to a new Mac.*
*With a little hoop-jumping due to Microsoft DRM. Legal, but annoying.