University, for the sheer amount of content it adds even if you rarely or never bring sims to Uni World itself. It's not the first EP I would encourage someone newer to the game to try, that would be Ambitions or maybe Late Night, but I played with Uni content for real time months before actually sending anyone to uni. There's the science, street art, social networking skills, herbs, gourmet coffee/tea in all their varieties, bowling alleys, comic book stores, table tennis, keg parties, the PlantSim occult state, the annoying but sometimes amusing mascot -- everyone seems to hate them, but ever try to seduce one to see if they keep their mask on during woohoo or when they fall asleep afterwards? I won't spoil the surprise. :)