1. M1 Fibre Broadband is pretty okay. I always recommend new users to consider M1 and StarHub first before considering other options.
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2. On the other hand, I heard many horror story of M1 previously and never recommended M1 mobile. It of course depends on location but general speaking M1 seems to be the worst among the big three (Singtel, Starhub, M1) but still better than SIMBA.
That being said, I started to try out the other three networks early this month while keeping my main Singtel S$15.28 line. Out of the three new lines I have, for local usage, M1 Maxx is the best even though I need to use the famous Airplane mode trick occassionally. But then Eight and SIMBA offer free roaming voice which is a significant advantage for them. Then it is also possible that both M1 and SIMBA mobile users will benefit from the upcoming merger (I expect the merger to be approved by IMDA in early 2026).
M1 Maxx S$10 5G plan >
Eight S$8 4G plan >
SIMBA S$12 "5G" plan (SIMBA 5G is kind of same as other providers' 4G).