Xcode is ok for C++ (not nearly as many features as Visual Studio on Windows, though).
The productivity boost was so great that I've decided to never use Xcode for C++ again and do all my development in a VM if I have to.
Best alternative is Qt Creator and it's probably what I'm going to use for my next C++ project on the mac. Many people recommend CLion, but I've never really managed to actually use it (and it isn't free and runs on the jvm).
Still VC++ is a powerful tool for C++ development, which is probably quite hard to beat, so having it on the mac would make using Windows totally optional :).