Having driven both, I will say that the S2k is way more fun to drive while the Z is more liveable on a daily basis. That said I would still take the S2k. Why? The S2k feels like an actual sports car while the Z feels like a rather large sports sedan with all of the practicality removed, and you can barely see out of the damn thing. It's kind of like driving a tank. If I wanted something more daily driveable than an S2k I would get an RX-8 over a Z.