I don't recall what my favourite pack was in the original game. I loved Makin' Magic but I could never get enough of the magic coins and I didn't know about the dragons until after I stopped playing.
In Sims 2 my favourite pack was Seasons, closely followed by Freetime and Apartment Life.
In Sims 3 it has to be Seasons, Supernatural and Island Paradise
In Sims 4, Seasons, Realm of Magic and Get Together. I'm not predictable at all. ;)
I loved the story element of Castaway Stories but the game was less fun to play in the sandbox mode. I've had fun with The Sims Medieval as well but I wish that one was more sandbox.