I doubt our friend here actually will buy either of the cars. He's just asking a question for fun, a flight of fancy. I can't imagine someone who's going to splash out that kind of money not knowing a damn thing about the cars.
Anyway, since I'm in a good mood today, I'll go along with it.
If you want to go along almost any roads really really fast, the Evo with its advanced 4WD system, will eat almost anything else for breakfast. If you prefer the purity of driving, with lots of balance and feel, or you just like to go sideways, go for the S15, with its very good RWD balanced chassis.
They've both got 2.0 litre turbocharged engines, so both should still have lots of horsepower in reserve that can be eeked out.