I’ve been digging around trying to get Unity and VS2015 to work well together(finally!).
I’m assuming you have VS Tools 2.3
At first I could only get debugging working by using Debug > Attach to Unity Debugger
Was annoying to do this every time! F5 is so much more convenient
In Unity’s build settings, I checked Development Build and Copy PDB files(not sure if this makes a difference)
Then Assets > Open C# Project and Bam! The default debug option will say “Attach to Unity”. I changed this to “Attach to Unity and Play”
Also, you can turn off Development Build after this works.