No signboard in Geylang is good -- though I'm not sure I would go to the other location in Esplanade (it's overly touristy and not as good IMHO). I probably wouldn't bother going to the East Coast locations as they seem to be primarily for bus loads of tourists.
My favorite spot is Mellben Seafood out in Ang Mo Kio (it's a cab ride to get there -- but it usually only ends up being 20-30 SGD from downtown Singapore). I find the crab to be much tastier -- and the crowd to be much more Singaporean here:
http://www.hungrygowhere.com/singapo...od_ang_mo_kio/
Their chili crab is delicious -- but my favorite is the Black Pepper Crab in a white curry. You're sometimes faced with a long queue -- but I think it's worth it, and it usually moves fairly quickly.
Uncle Leong's is also meant to be very good -- but I haven't eaten there.
Cheers,
-W