You need to drive the new STi. I haven't driven the '15 WRX, but have some seat time in the STi, and it's everything that Subaru go-fast fanatics have been asking for for ages: the chassis that the engine deserves.
The STi looks harder to live with day to day, but the goodies you get make it worth it, imho. The torque vectoring and DCCD AWD system alone are worth every nickel. Add in the rest of the stuff, and it's a great buy.
The older STi was a "see saw the wheel" car when driving hard. The new one? A Samurai sword in comparison. Sure, it's still got a little more body roll than the knock-your-fillings-out slot cars, but the car is SO much faster in the corners now, I'm sure there's plenty of giants that are about to be slayed.
Bonus? The old 2.5L driveline is known for being unbreakable and has a TON of not-horrendously-expensive go-fast goodies that make it pretty easy to turn the car into a 450hp beast.
Get the base car with no wing. It looks awesome.