That CIMB card does not look like it has any minimum spends or annual fee, really a good fallback cashback card.
Idea is, you lose out on rebates if you want flexibility.
Highest cash rebate cards usually come with very high minimum spends, or restricted to type of spends.
A balanced rebate card should be something like UOB ONE, if you want some sort of spending flexibility, just meet the 300SGD/mth requirement.
SCB Bonussaver also good if you have loads of spare cash on hand, but 500SGD/mth harder to meet.