I recommend St. Joseph's Anglo-Chinese Primary School (觀塘聖若瑟英文小學)
Some top boys from this school were mid-joined to LS ,YW and other good schools in the past years. And the level / discipline of this school is not bad!
Being a "new" primary school, YW is stiving for excellence in recent years. Most of YW boys are bright and smart, I believe. I am not so sure of YW secondary school because of the low-profile style of the its principal. It seems that the secondary boys are not particularly bright. Please correct if I am wrong.