Pls help me out - Best cc recommendation for a single working mom? Another note, thankful and really appreciate this sharing platform to help us all stretch our dollars :)?

Have your UOB One card as your primary usage credit card!

And it will certainly be advantageous to top up your grabpay account using UOB One card to seize the additional 5% interest.

If OCBC 360 savings account earns you your interest that you deserve, then fine. Otherwise, you might want to consider using UOB One account to earn the interest since you have the opportunity to fully utilise your UOB One card. However do note that there's a need for $500 spending on your card per month, plus 3 GIRO transactions monthly.

You have the UOB one card which is good!
For the CIMB signature visa are you able to regularly hit the min spending of 800? If you can then it's good. If not you can consider the maybank family and friends card as it offers more flexibility (you get 8% rebate with $800 min spend and 5% for above $500) and it includes more categories (groceries, dining, phone bills, transport, Netflix).