OUR UNOFFICIAL ANSWER
I would think that it would be good for you to live near your son's school so that he does not have to travel 45 minutes or an hour to school and also to have plenty of friends in the neighborhood.
Kowloon Tong, Beacon Hill, and Broadcast Drive in Kowloon are all near the Australian International School and are nice areas. The rent varies a great deal, from HK$14 per sq ft upwards to HK$41/sq ft or more. So for a 1,500 sq ft 3-bedroom flat, it will cost HK$21,000 and up. But the price may change up or down by 10% by the time you move here.
All these areas are quite accessible to the MTR (subway) and can get you to Causeway Bay in about half an hour. If you plan on driving, it may not save you much time unless you go early in the morning to beat the traffic (you will have to cross the harbor.)