I have to say expansions.
There are GPs that adds really nice additions to my game and I like having them but they have never added something that I absolutely love and it a must to my gameplay or add something that I enjoy using over and over.
Expansions though yes. Seasons adds just so much to enhance my gameplay. Get Famous is another. Though I don't use fame for all my sims or have all my sims go into acting or use the media stations I enjoy all of them so much and love making sims who are actors or content creators. Another is Get to Work, the active careers are nice but mostly I love running my own stores.
