Speaker wise, I'd say look at
LCR speakers for the fronts three speaker as this will give you the best balanced sound experience. You will also find that in using three dedicated
LCR speaker, your avr shouldn't need to be as powerful (even though it will have to have some ability in that size of room - so an
avr with headroom is also important) or work as hard with the room eq
I would say that spending time on looking for the right subwoofers that will match the
speaker/
avr combination so you really create a dynamic sound which can stop and start on a pin allowing for those crashing sounds to engulf the room. A good starting point would be
SVS, but with
subwoofer's you will get tone of recommendation, but the main advice is to use a dedicated subwoofer brand over a speaker branded woofer as they're never as good in my honest opinion
For the Atmos speakers, don't feel you need to use the same brand as in truth it really doesn't matter. What matters more is making sure you use the larger 8"
ci speakers as its a large room and you will benefit from it
If you can
wall mount the TV I would, it'll save on any freak accidence of someone knocking it over plus to me, they always look better even if you are still going to place a
cabinet beneath it