what is the most reliable telco postpaid currently?

budget around RM50+ a month as I am a light user.
Just need the line to be strong when I need it for mobile data, calls etc.
Currently on Digi but recently find their line not as strong as last time.. sometimes get 1 bar or 2 bar then internet can't even load.

Living in Selangor area but occasionally might go to Ipoh or Kuantan.

Heard about Yoodo, but people say the standard Celcom postpaid is better? Kindly advise. Is Celcom still having the best coverage in Malaysia?