I personally would NOT recommend Hong Kong Ballet, due to the fact that most ballet learners in Hong Kong quit once they pass their Grade 6 exam, and that to obtain Grade 6, in most cases, are solely to get themselves into a good Secondary School. (Since non-academic activities are valued high in Secondary Schools)
Shanghai however, is different.
There are people who learn ballet because they want to earn a living by performing ballet.
Beijing might also be a good choice too,
this video shows a 14 year old from Beijing during the Tao Li Competition