Which expansion pack is your bet? I'd choose Generations. I think that Generations is the best yet. It expands your family options in the sense that family life is more fun, it has a lot more interactions between family members and it makes your Sims seems more alive than previous expansions, it also adds a lot of stuff for the kids to do, new clothes, costumes, proms, dating, giving flowers, pulling pranks. Lastly, without that there a lot you could do with kids and teens accept grow up.