"Better" is a funny word because, by itself, it doesn't tell us anything. The problem is "better" depends on the goal you're trying to achieve and, without knowing that goal, we can't say which is better.
Let's say you have a jet and you want to calculate how much the passengers are going to weigh, in order to know how much fuel you need. In that case the average weight of the passengers would be more useful.
Let's say you have a tutoring service and you want to help students with grades in the bottom 50%. It doesn't matter what the actual grades are. You're just making a list of students, sorted by grade, then helping the bottom half of that list. In that case the median grade would be more useful.
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Note: This is why arguing about which thing (ex: a sports team) is "better" is meaningless. One could argue about which team has a better winning percentage, but without an actual numerical comparison, each person is really arguing about which team they themselves like better. The "better" team is different for each person and each person is making a true statement, so the question of which is right and which is wrong has no meaning. The question of which food, or which dress, or which political candidate is better is meaningless unless a particular goal or criteria with a testable number is identified first.