I have all of the except for Eco Lifestyle. Well, it depends 'cause it depends on what kind of stuff do you like your game, you know? But like, I think Seasons is definitely the most essential and it's one of the best, no doubt about it.
City Living is nice, the whole city and apartment life is kinda fun, and well, Elvira is a Vegas show girl so Get Famous is a nice one to have too! I particularly love Japanese culture so I'm in love with the newest one, Snowy Escape, it's stunning.
And for game packs, I like supernatural so Vampires and Realm of Magic are flawless; and for usual sim gameplay, Parenthood and Jungle Adventure are really nice!