I would say the quietest rooms would probably overlook the courtyard between BC and BCV. If you are talking quiet during the day, then some of the rooms farthest from the road, but facing Epcot, would be quiet as well, but these rooms really bear the brunt of the fireworks noise at night. I have actually had my bed shake from the noise during the Christmas finale! The pool view rooms can be quiet if you're on the upper floors, but depending on the guests in the pool, it can be noisier on the lower floors.
I usually request an upper floor, Epcot view. I'm up far enough that the road noise is minimal, and for the most part, I don't mind the fireworks noise (and sometimes, depending on the season and your room location, you can see the higher fireworks from your balcony). I had a great studio on the 4th floor once, just opposite the pool elevator, that had a HUGE balcony. It was fantastic for sitting outside and relaxing.