Like that better you buy the prepaid SIM card first, rather than signing up the postpaid one first.
https://www.yes.my/4g-lte-prepaid#addon

Buy the SIM pack, subscribe to the unlimited data plan from RM1 to RM5 per day, and then you test kaokao.
If you satisfied with the network performance, then only you subscribe the postpaid one, or consider remain as prepaid one and subscribe prepaid's konfem unlimited plans also can.
If you're not satisfied, then at least you didn't rugi as much as compared to sign up postpaid one.

For the postpaid one, you can choose either you want 12 months contract, or no contract.
If you opt for 12 months contract, you'll get discount or more offerings.
https://www.yes.my/konfem-unlimited-postpaid