I am a bit shocked at the things being said in this thread
Here are the facts:
(1) Floorstanding speakers are better than in-ceiling, that is a fact. Let's not try to debate that.
(2) Some in-ceiling setups sound FANTASTIC - if you havent heard such a setup, it does not mean it doesnt exist.
(3) inclined in-ceiling speakers are the way to go - the sound will not feel like it's fully coming from the ceiling (only slightly, assuming you position the speakers properly)
(4) In most cases, in-ceilings will sound much better than soundbars - you cannot compete with in-ceiling's sound separation/imaging, actual surrounds placed behind you (vs simulated surrounds), and the fact that you can get 7-9 inch drivers in in-ceilings (vs typically tiny ones in soundbars).
My personal experience/setup:
I originally had a goldenear setup comprising of two huge Triton One speakers (~$2500 each), a large supercenter XL speaker, and HTR7000 in-ceiling surrounds (~$500 each, 30 degrees inclined) . The front speakers really physically dominated the room, which i didnt like - especially with kids around. One day, I decided to stand next to my center speaker and face my surrounds, while playing stereo music only in my surrounds. Then tried the same thing for a movie (2 channel audio for testing). I was really surprised how good the HTR7000s were - they were not THAT much inferior to my Triton Ones, only slightly (assuming they are coupled with a quality sub). The sound was clear/airy, imaging was amazing, bass good enough for music but needs a sub for movies, etc. As such, I decided to sell my Tritons and center speaker, and went with the HTR7000 in-ceilings all around + sub. Aside from the fantastic aesthetic factor and saving $4500 from the sale, the system really sounds amazing and certainly does not sound it's coming fully from the ceiling (only slightly so)
Many very positive experiences from Goldenear's atmos all in-ceiling setup can be found online if you google it
PS: Martin Logans are 2-3X more expensive, including if you check ebay. My experience with their floorstanding speakers is that their sweetspot is very narrow, but in-ceiling could be different
PPS: If I bolted a black colored sound bar on my white ceiling, my wife would kill me