Which sim only MVNO has the best live customer service?

I think customer service is 1 aspect of a sim only telco that's rarely looked at when choosing a sim only plan. However I feel its important especially if u face porting issues. I had a number porting question to ask the sim only providers. So I did a little experiment to see which telco provided a live agent to talk to and I am now documenting down the results here. I was testing mainly MVNOs, so I skipped Singtel/Starhub/M1.