For Facebook: If the number of emojis (likes, loves, haha,...) is from fake accounts, strange accounts (strange to the commenter, meaning between 2 accounts with no or few friends in common), it may be ignored and not counted to be on top. As for the number of emojis from familiar accounts with many friends in common, that comment is easier to get to the top.
However, Facebook does not only consider the number of emojis, it also considers other factors such as: was the comment newly created or a long time ago (because newly posted comments will get to the top more easily); the number of replies to the comment also helps the comment to get to the top quickly, especially if the author likes and responds to your comment; the content of the comment is sometimes also considered and evaluated;...