There is this shop with an antique clock at International Plaza level 1 that sells Penang Laksa ($2.50) and their gravy is superb...u can also try their mee siam and mee remus.
I work near the Intl Plaza, most of the people I talk to (colleagues and office workers nearby) say the food at Intl Plaza level 1 is horrible, that people eat there because they have to....not because they want to.....
I've never tried of course because of their recommendations.
There is one popular stall in the food centre opposite Ang Mo Kio MRT Station, next to the theatre. It is next to a popular western food stall.
Geylang lorong 15
ban mian and xia mian good too
theres a stall at city plaza lvl 5 food court, not that bad,their ban mian also not bad, but standard dropped over the years, still better than average stalls though