Ask HN: Vagrant on Windows or OS X?

I am a front-end developer and I am about to start doing some contract work on a Rails web app. I currently use a Windows PC but I don't want to try and mess with getting RoR and the app to play nice with Windows. It looks like I have two options, I can use Vagrant and stick with my pc or I can purchase a MacBook for OS X.

I would rather not have to buy a new MacBook right now but I certainly don't mind if it would be best. My main question is, would there be any advantages to using OS X over Vagrant and Windows?