Chicken Rice and Chili Crab are the most Singaporean dishes I can think of, really disappointed that they aren't on here.
Katong laksa on the other hand (which is in the article) is probably the famous hawker dish that is most uniquely Singapore.
Incidentally, the Katong laksa at Cassia in Santa Monica is probably as close to the real deal as you can get outside of Asia. But be prepared for sticker shock.
Funny enough, many of the chicken rice vendors in Singapore sell a Cantonese-influenced version (though many places continue to label their chicken rice as "Hainanese chicken rice").
From what I understand, the Cantonese-style steamed chicken gets dunked in ice to keep the gelatin in the skin. The rice also tends to be slightly wetter and more flavourful.
The chicken rice I've had in Kuala Lumpur, Malaysia, and in some other "Malaysian" restaurants around the world, tend to be dryer and yellower.
I had a great tasting chicken rice, but it lost a couple points for having a head and spine laid across the side of the plate. Fine, just wasn’t expecting that!