That must have been a mistake. I did say any computer in the world but I then listed only two options to choose from, so even if I say any computer, you still have to pick from the options I listed.
But then it is a self-contradictory question, and I think it's reasonable to call it out on that.
I think what you meant to ask was "If you had a choice between the fastest Mac Pro and the fastest PC, which would you choose?"
This is how a lot of misleading/biassed reports end up in the news and advertising: "When offered the choice of any computer in the world, 61.4% said 'Mac Pro'"... So yes, sorry, how questions like this are constructed is
very important.
...but apart from that, part of my point was that the result is meaningless without gathering any information about what people want it for - or even what you mean by "fastest". A Mac Pro with an afterburner is likely to be faster at dealing with ProRes video than the "fastest PC" but as much use as an inflatable dartboard if you need CUDA. The Mac Pro isn't great for gaming but then the "fastest PCs" may be optimised for server loads, extreme multi-threading, CUDA etc. and might not be wonderful for gaming, either. The higher up the performance range you go the more important the question "faster at
what?" becomes. (See: is the Studio Ultra faster than the Mac Pro...!)
Anyway, I see there's a third option now and I'd like to change my vote to the Apple II (retro-computing can be hugely fun and an Apple II in good condition isn't to be sneezed at).