I voted for the top of the building, but then I considered that this might be the sort of residential building where wealth positively correlates with floor number. Maybe it has are penthouses or something. They have enough going for them, so they can probably be patient enough to wait for the elevator.
If this was a building for normal people, then I would send the elevator according to the time of day. If it was in the morning (around 8:00 maybe), then i'd send it towards the top, because people will be leaving for work. And likewise if it was 18:00 i'd probably send it to the ground floor, because lots of people would be returning from work.