Well this will open a giant can of worms :-)
Honestly, either system will do what you want in terms of processing power - it really doesn't matter. Cost wise, you will probably get things a little cheaper on the PC side but if you go for the higher end units and parts the savings won't be huge.
This is what it comes down to. Which operating system do you like using, and do you already have an environment (software, phones, music, other hardware, etc.) that would be easier to go Mac or PC? Answer those two questions and that's your real answer.
If you have no preference for any of those things, then you can get a price saving on the PC, but use the two points above to make your decision. Any other advice one way or the other is truly irrelevant.