I actually use both.
My Desktop at home is a PC. This is the computer I do most of my photoshop work on. My work computer is also a PC.
My portable is a MacBook. It goes with me where my camera goes in the event I need to look something up on the Internet or quickly upload pictures to the computer.
I am hoping to upgrade to a Mac at home within the next couple of years (maybe after I win the lottery
)