I always love Seasons and Pets. I haven't gotten Get to Work yet but it looks like a lot of fun!
I loved late night, the fact that I could have my sim live in a skyscraper was so rad to me.
I am a huge fan of pet expansions!! Loved it in both Sims 2 and Sims 3, expcet the horses would always crash my game in Sims 3. I'm excited to see what/if they do it for Sims 4 :)
Seasons has to be one of the best. The new weather made the world feel a lot more real
For TS3 I really loved Seasons. For TS4 my favorite purchased content so far is Get to Work.
Late Night was my favourite expansion for the sims 3. It added so much and living in the city was very fun.
I enjoyed all the expansion packs for Fallout 3 and New Vegas as well as Oblivion and Skyrim. I always find those expansion packs to be quality.