I'd start with a PC. A PC will be a great tool to start with, and I bet you'll end up using it more than a rotary. I started with a rotary, and when I got the PC I parked the rotary unless the task is very challenging. The PC has a great tactile feel to it, the pads are readily available, and it will remove some pretty nasty paint defects.
A rotary is really only used when a lot of heat and speed are needed. Using it at that level is pretty rare. I'm glad I started with a rotary so many years ago, it taught me a lot, but I wouldn't recommend anyone to start with one. Like I said I parked the rotary, and use the PC exclusivly.