In ceiling speakers 70RT vs 90RT

Hi im in process installing home theater system, need to put all my speakers in ceiling do to lock of space on the walls.
Can't decide if is should spend a little more and get 3 x 90Rt and 2 x 80FX-Rt or would 3 * 70 Rt with 2 x 80FX-Rt be enough. Room size is 15 by 24 8foot ceilings. Tv 10 -12 feet away from the couch.

Let me know what u guys think