I use my mobile very often in work.
My advice is....
Ask urself whats ur mobile usage pattern?
Do you.
1) Make Multiple SHORT calls (less than 2 mins or 1mins)
2) Or Do you make Fewer calls but LONGER durations..(ard 30mins+) like explaining an essay to a client?
3) Do you need to call overseas or to someone roaming overseas? (Starhub has some plans with free overseas call)
If your pattern is That of (1), Then DO NOT, get Singtel. Go for StarHub
I made a TERRIBLE mistake of switching to Singtel's FREE INCOMING from STARHUB's FREE INCOMING. (thinking Singtel has better network and since both is free incoming why not)
Since my calls are mostly short and numerous, the 6 second block Charging by Singtel and the PER-SECOND billing of Starhub, makes a HELL of a lot of difference.
Try getting 400 calls (or more) rounded off per month, and the few cents isnt so cheap any more.
The bill Almost DOUBLED.
By comparing my OLD bill of Starhub and Singtel, my usage pattern hasnt change much, in terms of how many incoming and outgoing but the Diff in Bill is HUGE. I suspect its the per-second billing.