Depends on the week.
Summit is April 28 to May 01, which is about 1,000 teams, most teams are around 20 kids. This is a competition for ages 5 to 18, so a lot of little kids.
Worlds is May 8-10, not sure about the number of teams, but it is the older girls, ages 12+ and they are the more serious competitions.
Either way, it is going to be crowded and loud. These are the two biggest competitions in the world. I would argue Worlds may be better because the girls are more competitive and most have strict rules, i.e. no going in pools, only going to parks as a team, curfews; compared to the younger teams.