Hi! I am also a mom of 3 (12, 7 and 4.5). It very much depends on how big your wallet is when it comes to housing. With a limited wallet, I much prefer Pokfulam. Discovery Bay is also a good either but you will have to consider how to get the kids to school when they are older. The rent for large flats in South Side of the Island (ie. Tai Tam, Stanley, Repulse Bay) had gone down quite a bit lately so you might find some good deals there.
With schooling, all my kids go to English Schools of Foundation cos I do not receive expat package at my job so I cannot send them to anywhere else which requires hefty debentures. Moreover, ESF has a lot of schools in HK, when I decide to move out of my kids current school catchment area, I can always transfer them to the one in the other c.a. They are also changing their curriculum from British to International Baccleurate, which means your kid will be able to go to Uni anywhere in the World.
Hope that helps.