For me, I would choose the Mac Pro. I like it because it looks good, the bundled software is great, and I have no great urge to play the newest and greatest FPS. In my book an intuitive user interface comes first; when running OSX, I know I will get that.
You don't buy a Mac just because the hardware looks good or the software is pretty much immune to viruses; you buy it to get OSX. I think it is worth the extra bucks.