For expension pack I'd go in this order : Seasons, Get together, and City living
Get to work and Cats and Dog are great but they are very centered around the career available, or the pet you want to adopt.
For the gamepacks, id start by Parenthood. The rest are all good to but it depends of your interest really. Do you want a supernatural world, go on an archeologist adventure? The least interesting is the first one tho. Outdoor Retreat is honestly pretty dull and doesn't offer much more than an empty world with too little activities. Avoid that one, or buy it last.