We live at Siglap (East Coast) and send our kids to Eton House. It's the nearest school, that we found, which uses a British based system, and so far, we're happy with it. The kids were happy last term, and they've just started a new term, with new teachers and classes, and they still seem to be happy. I'm also pleased with their rate of learning too, as they have come on leaps and bounds since they started at Easter.
For some reason, people often slate Eton House. I'm not sure why this is, because so far, it's been fairly positive. I find the administrative staff a bit snotty and useless from time to time - but as it's not them who are teaching the kids - I let that pass!
We also seem to be constantly getting bombarded by invoices for more money from them or the bus company, which is a bit of a nightmare, but if your company are paying for it all, this shouldn't worry you too much (from what I've heard, it's the same with all international schools!).
I've heard good things about Dover Court and Chatsworth schools too - but we chose Eton House because it's so much nearer. The bus picks them up at 8.00am and they're at school before 8.30 usually. I'm not sure what the travelling times to the other two would be like, but I would have thought you'd have to add about 20-30 minutes on to that travelling time. However, having said that, I do see buses from Chatsworth around here, so some kids do the journey.
There's another British based school, which is Tanglin Trust. So you might want to check them out too.
Hope this helps.