Better Windows 10 Compatibility
The macOS Sierra 10.12.5 update adds support for an enhanced Mac App Store and makes macOS Sierra easier to use with the Windows 10 Creators Update.
In the new macOS Sierra 10.12.5 update, Apple fixes USB headphone playback, which is it's own reason to upgrade if you have problems and for a better Mac App Store in the future.
The macOS Sierra update includes an easier way to install the Windows 10 Creators Update. Once you upgrade to macOS Sierra 10.12.5 you can install the Windows 10 Creators Update without media while in Bootcamp.
If you use Bootcamp and Windows 10 this new macOS Sierra feature is worth upgrading for.