St Louis has many wonderful, peaceful, quiet neighborhoods. There is so much more than that though in deciding where you want to live. St Louis is one if the 10 largest metro areas in the US - we have a lot of diversity in our housing - from 100 year old Victorian neighborhoods, to brick bungalows that look like Gingerbread houses, to Mid- century modern, to new open floor plan construction homes.
Many people start by considering how close they want to be to work, school, place of worship or something else that is important to them. Then they consider the type of homes that they want to have, along with the amenities that they want in their new home, along with the neighborhoods that they are interested in.
When comparing condos, apartments and homes, it truly depends on how well they are built and the finishes that are used. When the finishes are changed, noise levels change. For example, as carpeting has gone out of style and hard surface flooring (such as tile, laminate and hardwood) has come into style, noise levels go up - not just in your apartment/condo, but in your neighbors. Carpeting and its padding absorbs a lot of noise, hard surface floors allow noise to reverberate and both the apartment/condo that the flooring is in and the units around it all become noisier as a result.
I love St Louis and I love to share it with others. If I can be of assistance with your move, pease let me know.