We applied for Tanglin before we got here. When a place came up, I finally got around to visiting and was very disappointed. In fairness to Tanglin, I think it was because I was expecting a prep school, rather than a state school with flashy facilities. So, I looked around UWC Dover (didn't like it for a 4 year old, too much of a concrete jungle), Dover Court (wasn't convinced by the teachers I spoke to), UWC East, OFS (too many speakers of ESL, poor teachers) and St Joseph's International. Our decision to go with SJII was pretty instantaneous, even though it meant losing the 2,000 odd $ we'd already given Tanglin. Small school, caring environment, I liked the IPC curriculum, Mandarin every day, the children were very international and seemed well behaved and polite. I also think it's less transient than Tanglin, as there are many more PRs' kids there.
Although I'm not sure I'd send my children to the high school, as it seems much more Singaporean and therefore pressurised, we've been very happy with the elementary school over the last couple of years and haven't regretted the decision to turn down the place at Tanglin (we could also have gone to UWC East).
As I was already here when shopping around and had some experience of the kids attending the various schools, I didn't even consider ISS, as it seemed to be very Euro-centric, even more so than OFS. To be brutally honest, most Brits go for Tanglin, UWC or SJII. I know of some that treat the Canadian School and OFS as a 'holding school' whilst places at the others come up.
If you're coming from left-field, I hear the German School isn't bad. I know a couple of teachers in the European section who obviously think it's good!
The French school is the cheapest if that's important, but I think the bilingual section is very over subscribed, even with French passport holders.
The Ozzie school always seems to have places, but it's in Serangoon and is definitely less academic than UWC, Tanglin and SJII - maybe just in the early years as they seem to start proper schooling later.