If you don't like imaginary friends - well, Seasons introduces Aliens and alien abductions. That can be a bit annoying at times - but can result in some extra fun - such as when my witch turned her elderly abductor into a toad on her return home. Or the time two of my male sims got pregnant with an alien baby in the same household at almost the same time.
https://www.carls-sims-3-guide.com/seasons/aliens.php
I think all of the expansions have lots of good stuff in them and some not so entertaining things.
I particularly like Ambitions because my sims can stay home and earn money by being self employed.
But having said that, I have ALL of the Expansions installed and wouldn't want to try to play without any one of them.