Toms Hardware just did a review of 13 mid-tower cases. Have you read the review? If not, there is a link to the review on the home page and over in the right hand column of this page. The Antec 300 did quite well.
As for a quiet case, the noise one hears is caused by the flow of air over, under, around, and through objects such as fan guards, fan grills, and components inside the case. It is the airflow which causes noise. You'll see posts where individuals who bought high airflow, high rpm fans will reduce the rpm to reduce the noise. Unfortunately they also reduce airflow at the same time.