A "top schools" a ranking is somewhat meaningless. You're going to get a good education at any of the ones that are currently way oversubscribed but what you should really be looking at is what is in the best interest of your specific child and the way they learn, along with your long term plans for the future.
For example, ISF Academy is a bilingual school, and even the teachers and administrators there would caution you "come here if you are ready to commit to a bilingual education until at least age 12 or so. The reason being they don't want to have a child move over to a fully-English language school midway through their primary years as they might not be on par with their peers in their language development by then.
Some children want to be on a path that is not going to disrupt them that far from their path "back home", so you see many British students at Kellett, many American students at HKIS, French children at the French International, etc. If you foresee yourself moving away in a few years you might be better suited at a school on the same curriculum rather than one that some others might perceive to be "a few notches higher" than others.
You might also have a child who needs a smaller class size as they don't stand out as well in say the 30 kids in ESF, or conversely, would be better suited in an ESF with 30 as that will be good preparation for their future schooling somewhere else with similar class sizes. You might also want to choose a school physically closer to where you are living rather than a supposedly 'better' school on the other side of the island, given the commuting difficulties and the chance for more play dates and out of school interaction with classmates. Some people don't like schools that have religious overtones, others don't really mind it (or actively seek them out).
My advice is to treat it a bit like you treated university applications. Apply for a few of the "reach" schools (schools you might not really have that much of a chance of getting into), a few "likely" schools (schools you might have a leg up on via passport or debenture or some other connection) and a few "safety" schools (schools you have a very good chance at getting into based on location, passport, debenture, etc).