When given the option to create a new character, Blizzard offers you a list of realms which are marked with their population -- but a handful of them, instead of showing population, are simply marked as "Recommended." However, these are marked recommended for a reason -- because they're small realms in need of new players. In fact some players on the official forums say that the recommended realms are simply ghost towns: places you can never find a group to do quests or instances, where end-game raids are non-existent, and where the auction house is empty of interesting goods (after all, there's no one to put them there!). But on the other hand, the recommended realms aren't going to have queues or lag issues -- and should hopefully be growing as new and rerolling players pick the clearly marked "recommended" realms.
But what do you think? If you rerolled today, would a recommended realm catch your interest? Or would you pick a higher population realm that had plenty of players and an active economy?