To me, i will do my homework first before i need to do a purchase, and each bank has it's own good deal la....
For Carrefour, posb is the best as it has 5%.
For Guardian & GNC and some big chain market in Malaysia, Maybank has 5%.
If u not only into Cash, this DBS capitalcard also offer good rebates but in Capital$, like GNC, they have 10% capital$ rebates.
For those point systems, if u do the math, u will notice actually $5 = 1pt is like 0.5% cash exchange where Amex 2pts is close to 1% cash exchange, it just that u have to accumulate more lo.
Dun forget UOB also got UOB smart$ also, that is in other cash form.
So as you see, 0.3% cash rebate is too stingy le, i will use amex to get point instead.