STi- Very fun car, but kinda lacking soul. I put 13,000 miles on one, and while I loved it, the whole time I was missing my 2000 M3. In terms of the power, the STi is amazing. Very little turbo lag, and the most amazing part is the torque: 300 lb/ft out of a boosted four, and peak is at 4000 RPM, IIRC. Feels like a V-8's power delivery.
The Legacy GT- Uses the same
block as the STi, but does not have the Variable Valve Timing of the STi and does not feel nearly as quick to me. My parents have an '05 GT wagon and a good friend has a sedan. Beautiful cars, really nice interior, but not quick enough for me. If you go that route, try to track down a year old Spec. B model. The '06 has a 6-speed and some other goodies, but the price is over $30K.
I owned an SRT-4 for a week. I really liked a lot about the car, not the least of which was the price, but all it wanted to do was spin the front tires. It got old realy fast. And it was still a Neon, even though Dodge doesn't like it when you say that.
The GTO is truly an amazing bargain. You can get an '04 with the LS1 (5.7 liter, 350 hp) in the high teens very easily. Going to an '05 gets you an LS2 (6.0 liter, 400 hp) as well as better looking dual exhaust and hood scoops which help the car look a little more masculine. You should be able to find one of those in the mid-20's very easily. A lot of bang for the buck to be sure...it'll put a huge grin on your face, and a lot nicer to drive than a blown '03 Cobra.
Don't buy an Elise as a daily driver. Trust me. I tried it for a while. It gets old...fast.
Once you drive a BMW, it is hard to drive much else. I'm on my second M Roadster, and I have no regrets. The styling is subjective, but in my opinion it was the last attractive BMW (pre-Bangle). If you can find a '01-'02 (they only built 1200 in two years) you get the S54 motor out of the E46 M3 (333 hp, 315 in the Roadster). With decent miles, you should be able to get one for under $30K with low miles; I bought mine with 22k miles. 0-60 in 4.6 seconds, 174 mph top speed (de-limited...Dinan chip), the most amazing sound as it winds up to 8000 rpm, and all with the top down. BTW, the motors all have a 100,000 mile warranty.
Hopefully my various personal experiences help you in your search. I love car shopping!
-----Matt------
My two straight-sixes: