Go left. I'm thinking of the UA flights I have taken from both HKG and NRT. If the flight goes in straight (meaning, south past the east coast of Johor and then due west into Changi), then I don't think it makes much difference. However if the flight overshoots Singapore and goes over Batam and Bintan Islands (Indonesia, south of Singapore), it will fly north. Somewhere over Singapore airspace the plane will hug Singapore's southern coast going eastbound before landing, thus the suggestion of sitting on the left side. BTW nice view of the Marine Parade and Bedok districts just before touchdown.

So: direct in approach, either side is ok, but an approach that uses the Indonesian islands to swing back up, sit left.