I think what the OP needs to do is a lot more homework on both cars in question and then the decision will be made naturally. At the moment I get the impression he has looked at photographs of each without really knowing much else and thought 'I like the way both those cars look'. In every other way they are quite different.
The Impreza is available in a plethora of different trim levels from just 200bhp right the way up to big power. He wants a WRX as thats what Colin used to rally - well no, Colin didn't drive a WRX he had a WRC which is a different beast. Therefore you don't need to get a WRX to get what you are after at all, a UK Turbo 2000 is easily affordable in budget and probably less faff than an older WRX Import. These cars are very thirsty and can be very expensive to run, but are very quick.
Next up the Lexus IS200. It is completely and utterly different to the Impreza. It has a better interior, it is more refined, it is better built, it is rear driver, it has no turbo, it has more cylinders, it has loads less power and is considerably slower. If you are happy with the performance of the IS200 then buy it as it'll be considerably less hassle to own than an Impreza, and much cheaper to insure and run.
I appreciate that sometimes you just might have two differnet cars on a list but these are so different from each other its hard to compare them. I don't think the OP really realises how different they are.