<font color='#000000'>I have owned several inwalls at both my current and prior homes. First of all, even the best do not compare to a mid-fi freestanding speaker. The cabinet is quite important, and walls or ceilings are less than ideal. I know, the wife factor tends to require sacrifices!
The brands I have owned are Niles, Klipsch, Speakercraft, Sonnance, and PSB. The Speakercraft have been the champs, although quite pricey (AIM series). The Sonnance are also pretty nice. I did not care for the Niles or the PSB, relative to the others. Each of these brands carry a pretty wide range, from cheap to quite pricey.
You did not say if or waht your other speakers are. Are the in ceiling just for rears? If so, IMHO, it really does not matter that much. If they are fronts, be sure to get a speaker that has a tweeter that swivels so as to direct the sound toward you and not just straight down.
I have also been told that NHT makes a decent inwall/inceiling speaker. Not sure it makes much difference going with a niche player, just plan on spending way too much for the privledge of hiding them.</font>