your final choice will likely depend on the earlier discussed factors , usb peripherals and customizability or mobility and less hardware to worry about.
you may have more factors in mind but thats what I could think of that define the options pc and tablet from the top of my head.
personally I would go for pc at this point in time given the hardware and software options out there right now.
I will keep an eye out on the tablet market to see if there are any interesting developments.
Right now a pc is the only device that I can customize easily, upgrade if needed and does everything I want it to do.