Everybody has their own choice of Wallpaper, mine changes on a regular basis. At present I am using quite a dark wallpaper and the normal light Mac Menu Bar and Dock seem to visually jar with this but there is an option in macOS Sierra that enables this to be changed.
The standard look of the Menu Bar and Dock is shown below. Firstly, click on the System Preferences icon in the dock (img.1).
When the System Preferences window appears select the ‘General’ icon (img.2)
In the ‘General’ options check the box ‘Use Dark Menu Bar and Dock’ and the Menu Bar and Dock will become dark and fit in with the overall look of your desktop (img.3).