The original question is kind of a dumb one (no offense intended) because it asks which car
handles better around a track. This would mean, which car is faster ONLY through the turns in a track. The question should be, which car is faster on a track, which car is a better handling car, or which car is more nimble, etc.
Obviously the S2000 is more nimble, no getting around that. The Cobra has much more power, so it doesn't take a smart person to figure that out.
They are two completely different kinds of cars, built for completely different reasons. This is like comparing an apple to an orange here.
I voted S2000 because I used to have one and it was very fast (200 pounds reduced, 400HP/285TQ)
And I've ridden in Mustangs and they feel like you're riding in a boat (I just like small, nimble cars better but it's my personal choice).