If you were using a provider previously, i would recommend you
to continue with that provider.
But i would say that singtel's price plans are a little on the
expensive side. And most old routers support only up to 100mbps, so
200mbps means you might need to get a new router.
I'm not sure about starhub. But M1 connects through starhub.
M1's prices are a little cheaper than starhub.