Visual Studio 17 has been supported from 4.14. With 15 being default but can swap to 2017 if wanted.
Version 4.15 supports both Visual Studio 2015 (default) and Visual Studio 2017. If you are building the Engine from source code, you would want to open a command prompt after running Setup.bat and run the command GenerateProjectFiles.bat -2017. This will give you a Visual Studio 2017 solution for the Engine.
To use Visual Studio 2017 for projects, you can set your preference for which version projects use by going to Edit → Editor Preferences → General → Source Code and choosing Visual Studio 2017 in the Source Code Editor setting.