Miata-Yes, the top went down and it was a very competent vehicle, but at the end of the day it was just an appliance. Emotionless.
Corvette-Fun car, but the used ones I test-drove were plasticky rattle traps on the inside, and drove like trying to do brain surgery with a pickaxe. No subtlety or precision feel. They also seem have homing devices that keep drawing them to trailer houses.
S2000-See Miata.
Z350-Decent car, but nothing terribly special to look at or drive. Just didn't do anything for me. Also, still can't quite get over the chest hair images of the 70s Z cars.
In the end, the Boxster just drew me in emotionally in looks, feel, and performance. Doesn't hurt that I was a 911 admirer since childhood.
Still smile like a lunatic every time I look at it or drive it, so I guess it was the right choice.