It seems that there has been much competition in the telco business in Malaysia as there have been quite a number of changes in the plans over the past year or so. However, I think U Mobile and DiGi still have the most value-for-money internet data plans for prepaid SIM customers. Anyway, I have already updated my guide over here. Good reference if you need prepaid SIM in Malaysia.
For my recent trip to Bangkok, I planned to get a local prepaid SIM card after reading online how affordable it is. But when I arrived in Bangkok, what I saw seems to be slightly different from my researches. Anyway, it's not uncommon for real conditions to be different as information may be outdated at times. At the airport, the 2 big operators have booths next to each other. From what I saw, most of the plans are similar, so I guess any choice between dtac or AIS is ok. However, I spotted a low usage plan for AIS and wanted to purchase that. Unfortunately, that SIM card package is out of stocks, so I had to settle with the 1GB plan.
I managed to grab air tickets to Bangkok during one of the Scoot's weekly promotions on a Tuesday. Fortunately, the earlier demonstrations have toned down and the bigger scale demonstration is from 13th Jan, so tourism is not much affected. After landing in Suvarnabhumi Airport, we spent quite some time queueing for the immigration customs. After clearing the customs, I managed to purchase a prepaid SIM card before leaving the airport via the City Line.