It's so hard to rank them.
Island Living (I like the world and beach activities)
Get Together (the club system is useful and I love the world)
Seasons (sometimes the weather is annoying, but it would be so different to play without it)
Get Famous (I don't play famous sims all the time, but I like playing them)
Cottage Living (I love the rabbits and chickens, but I don't like the quests that much)
Discover University (It's actually surprising that I like uni a lot, I thought it would be boring, but I have had good uni years with my sims)
Snowy Escape (I really like rock climbing and some other stuff, but the festivals not that much and I think the world could be better)
Horse Ranch (I bought it yesterday so haven't really played much yet, but I'm excited about nectar making and well the horses too)
Cats & Dogs (cats and dogs make good familiars)
City Living (I love karaoke and some of the cas and bb, but I don't usually play much in San Myshuno and I have kind of seen the festivals already)
Eco Lifestyle (I use some of the cas and bb and dumpster diving is fun, but that's that maybe)
I only listed the ones I own, so Get to Work, For Rent, Growing Together and High School Years didn't make it to the list. I might be interested in For Rent or Growing Together.