If you take a look at the "offers" and "star buys" for their road shows, you would notice that most of their phones are usually more expensive than what M1 or Singtel is offering.
Also, they are getting less and less generous in giving out vouchers. My dad who spends an average of $50-60 a month received a paltry $50 voucher from starhub.
My friend told me that he got a $100 voucher from M1 and he averages $45-60 a month. And he did not even need to ask M1 for the incentive. It was automatically mailed to him when his contract was about to expire.
Im not sure about Singtel, but generally, is Starhub getting more kiam?