It depends on the whole story, not just stats/rank. Sure, sometimes the easy choice is someone in the top 5%. But if you go straight to what Harvard itself tells that they look for (right on their web pages,) you can get an idea what truly distinguishes one tops stats kid from another, what “might” make a 2nd decile kid a good choice over some higher ranked kids.
Without that understanding, how does one even create a good app- over the hs years and when writing the app? You have to think like Harvard.