I think that a wrx is the way to go over the sti. My friend has an 02 wrx with a few bolt ons and a cobb reflash. He pulls on stis like no ones business and he definitely under the cost of an sti. Sometimes I wish I could have found an 02 wrx when I was looking for a car. Those are the best models in my opinion.
sti is a completely different car. throw a few bolt ons and a cobb reflash on an sti and see who wins. my dad got his for 23k at 29k miles about a year and a half ago. other than one dent on a door the body is flawless so this wasnt some beaten car that was sold cheap.
wrx trannies are crap. and dont think the engine is the main difference. wrx's handle nothing like an sti.