the wrx is an all around good car but probably not the best car if you want only the most power or fastest times.
I bought mine because its a comfortable, well handling, decent power car with great aftermarket support.
the evo is smaller in the backseat and cheaper interior.
However, it is faster and cheaper to mod, but expensive to buy into.
locally evos are going between 16-21k for 03-06 models. similar to an STI, but way more than a wrx.