how much do you want to spend, some good fluid, pads rotor and caliper prep on the standard gtr will work btter than you expect but if you have $3000-$6000 for a set of AP/brembo/alcon etc etc etc which are excellent but another ball park as in terms of feel and performance
as you said only street driven most of the time, if i were you work on what you have eg bigger rotor, pads, fluids, seals as the price of the bigger units wont offset the street performance.
having said that how nice is it having ap/brembo alcon under the wheels.
just my two cents.