Let me give this a try.
I love my Boxster because:
1) The handling is absolutely amazing. It handles so well, I can now honestly say that I know what people mean when they talk about the car being an extension of the driver. No other car has given me that feeling.
2) I love twisties! Exhilarating is the only word that I could find to describe the feeling of blasting around corners in this car.
3) It's a Porsche. As has been said many times there is a certain aura of mystique that surrounds Porsche. In LA you seen tons of BMW's or Mercedes on the roads, so much so they stop catching your eye. But a Porsche will still turn heads.
Compared to:
BMW Z4: My father has an 03 Z4, and while it's a great car in it's own right it just can't measure up. The steering is not nearly as tight or responsive as the Boxster, nor is the handling through the twisties. Also, I don't feel like part of the car while driving it. It's fun to drive, it's just not "exhilarating".