I didn't check out the Emporium, but EmQuartier is more about all the great international chains than the actual Thai food court. If you go to the basement, the traditional Thai food court is on one side and kinda meh, but on the other side is a separate food court with a bunch of famous international chains.
And if you go up to the Helix section of EmQuartier, there are also a bunch of great sit down restaurants.
IconSiam has a food court people rave about, but it felt really touristy to me. Worth checking out just to ride the free ferry if you have time.