For what its worth....I like them both but it just boils down to what you prefer. My good friend has a 2000 s2000 with a hardtop and a few mods..The car handles like it on rails but ride really rough (aftermarket springs and shocks) The interior is a little tight for me (6'4" 220 lbs) the car is very quick provided you keep in the power band. Reminds me of the RX8...I also looked at both and the Z was all around the better sports car for ME. Love the HP and Torque..not to mention its the perfect size car. My s2000 buddy REALLY likes the Z as well...
Both are great cars in my opinion.....