Niles is dedicated to ceiling or in-wall speakers. Their high definition speakers are very good. I'd rank them ahead of the other two.
Klipsch makes good products but my experience with their ceiling speakers was at a dealer. They sounded detailed and good but not as good as the Niles. The Niles sounded more complete.
JBL ceiling speakers I have not heard. I'm sure they are decent for suround or rears but I'd have to hear them before I would consider them as mains.
Ceiling speakers are a different animal, so going to a dedicated manufacturer with a good product-line inproves your chances. Like Niles or Speakercraft. Also, don't forget about the installation. From my experience ... talk to them before installing, they have a lot of info that is not in the manual.
Cheers.