Depends on the way the winds are blowing. Three of my four landings in SIN in late 2008 were to the south.

Sitting on the left while landing to the south is kinda useless--you see the tip of the SIN island and a bit of Malaysian wilderness and a lot of open ocean beyond that.

Sitting on the right while landing to the south is less dramatic than the above shot, since you don't see any of the big tankers/cargo ships and don't really get a good view of the city itself (since it's a good bit west and south of the airport, and you're coming in from due north, not circling around from the south), but you can see a bit of Johor Bahru and get an interesting comparison of construction and the lay of the land of Malaysia versus Singapore across the strait.

If I had to choose, though, I'd pick the left, since the potential positive of that view if coming in from the south exceeds the potential positive of the view from the right if landing from the north.