Well I voted for the Apartments (I had been making apartment style houses for my sims the month before I heard about Apartment Life (and btw it was the ads in the loader that alerted me to the expansion...nice one EA)) but the thing that really blew me away was ceilings. I hadn't heard anything about what new features AL had, I just was building zoomed out the first day I got it and I zoomed in and got a nice suprise!
It's the little touches like that or the upskirt cam (er, I mean the 45 degree up angle build cam) that make the game interesting. Plus if this is the last expansion for Sims 2 what better way to cap it off than to literally cap it off!