All 4 resorts are crowded, so it's difficult to pick one out that is less crowded.  All have long lines for check-in, long lines for buses, long lines in the food courts and crowded main pools.  The All Star resorts have 1920 rooms each while Pop has 2880 rooms.  That being said, I stayed at Pop one year where they were so overbooked that they were "walking" people to other resorts (both in advance and in person) and it did not seem any more crowded than my stays at the All Star resorts.  I would use theme to choose a value resort.  Also, it is my opinion that a preferred room is only worthwhile at All Star Music (because the Broadway & Country buildings are so far away) a waste of money at the other value resorts.  Even the farthest building is an easy walk to the food court and bus stop.