[Giller]

Of the three, the Boxster is the only true sportscar. Mid engine makes handling fantastic, it has a good weight to it and lots of pure, raw power. As much as you say power is a non-factor....it's always a factor when push comes to shove.
The Boxster will cost you more both to buy and maintain. It will also put the biggest smile on your face as compared to the other two.
It's almost impossible to directly compare anything Japanese to a true German sportscar. The Badge does mean something.