The deed of mutual covenant is the key
Quite a few older buildings and estates restrict keeping pets (especially large dogs) in their deed. Always check the deed and the management office's rules before signing; this matters more than the district name — different estates in the same district can differ enormously.
Outdoor space and dog parks
Vet and pet-service density
When choosing a district, check the walking distance to vet clinics, pet shops and boarding services — these are hard needs in emergencies, especially late at night or on holidays.
Commute and pets
Routes for taking pets to work or training grounds, and public-transport rules on pets, all affect daily life; the New Territories offers more space but is further from the urban area, so weigh the trade-off.