I want with Get Together mainly for the club system -- I've found it quite useful for my families, especially for siblings. In one save I started with a brother/sister combo; they shared an apartment for a bit then they both married and moved to the 'burbs. I formed a group, Sibling Revelry, for my grownup Sims and their spouses, and then when they had children they went into a separate club, Cousins & Such.
Close second is City Living, because I enjoy having the apartments for my single Sims. It also has some great features -- the food stalls with more recipes to learn, the Vegetarian trait, the career system where you can either go to the rabbit hole job or "work from home" with assigned tasks so once you're done, you get the rest of the day free. (There are mods at MTS that extend the CL career options to many of the base game careers -- they've breathed new life into the old boring careers.)
