"Specialty coffee shop on a discreet 2nd floor behind HIll Street's famous Pork Noodles."
As far as coffee goes, this local hideout on the second floor, a stonesthrow from Tai Hwa pork noodles, is as good a cup of coffee as you'll get in Singapore.
These recommendations are just personal opinions based on my palate, things change, chefs get fired or replaced, places open-close, relocate, so take it all with a pinch of MSG and discover your own gems too. But please do try a few of these, they have been researched exhaustively.
"Tastes are subjective, so take everything with a pinch of salty tears"