As a fresh grad, earning about $2.8k with a monthly spending of $1.2k and travels about once a year, I am looking to sign u for AMEX True Cashback card. Is it better as compared to POSB everyday?

It depends on the categories which you spend more on and the merchants you frequent. Or you can have both cards, for those spending categories that POSB provides lower rebates with, use AMEX...

It depends on what your spending habits are like.

I just recently cancelled my True Cashback Card. This is because not many merchants accept Amex, hence I prefer to use SCB Unlimited Cashback