I would guess you'll have less compatibility issues on a Mac, using a virtual machine to run Windows, as OSX can be quite picky about the hardware it will actually run on. So if you're opting to build it yourself and not buy a hackintosh ready-made, it would probably be easier to buy the Mac.
But... building a hackintosh is probably cheaper than buying a Mac so you should consider that too.
The hardware in the machines is virtually identical, don't let Apple try and convince you otherwise... they all have CPUs, RAM, Hard Drives etc... often made by the same companies...