I sometimes use VM-Ware, and my main complaint with it is the plethora of files it creates. VBox is much simpler to manage. That said, I have not done any critical comparison for performance, but with our very large and slow-building project here, the build times reported by those on VM-ware correlate closely to those we see on VBox. One reason I prefer VBox is that the video driver in VBox has always seemed to be a better design. When I tried VM-ware years ago, the finite choices in resolution offered at that time were purely unacceptable.