one problem with the WRX is that our tranny is not as strong as the STi. If you can afford the STi go for that but if you can't get the WRX. What are your plans for the car? If it is DD then the wrx is perfect. But if it is a track car, get the WRX. Read up on stickies and this forum. I learned A LOT from these guys/girls. And if you have a question, use the search button. Chances are, they might have been answered already.
The only con to the 09 is engine failure. There is a thread on NASIOC about it but can't find it right now.