There is no objective criterion according to which we can determine it, in the end it is a matter of preference. However, we can stick to some objective data that would support this hypothesis, such as the fact that soccer is the most watched sport as Russlenat has also pointed out. But this may change historically. The most popular sport in ancient Rome was Chariot Racing, just as gladiator fights were very popular, and those sports don't even exist today. We do not know what may happen in the future.