If it didnt have to have a backseat I would say miata. But if it has to have a backseat, neither of those are bad choices. The SE-R gets a pretty bad rep, but it's actually a decent car. My brother got an 02 spec v when they first came out and he autocrossed and tracked it and it did really well. But honestly if I was in your position I would try and find a decent s14. Theres endless possibilities as far as modifying goes and they can be made to handle very well.