I have had great experience with my WRX, with some mods.
Mods such as Tires,track pads, better strut and spring combo, and swaybars go far.. with a little less restrictive exhaust i.e. uppipe, downpipe and turbo back with some Engine Management it really wakes up the car..
Car is streetable, not to loud, and a whole lot of fun.. so much, my wife enjoys driving it
At the track it is quite good.. Can tackle and pass most cars.. your limiting factor will be the driver.. in good hands it plays well with most..
an 02-03 can be found for 16G's give or take.. about 3-5 grand for upgrades.. and your having fun.. again it all depends on what company and parts you pick..
if you have money and do not what to modify to much then the STI may be for you.. less streetable, but comes as a great package.. other in this price range also include the EVO
That would be my recommendation..
ALex
Plus it is a flat four.. can't go wrong with that..