5.1 vs 3.1.2 surround sound
Hello, I am new to this and have a question please. I have budget Onkyo tx-sr393 receiver does Support Atmos and my speaker set up is 2 front speakers mounted flush in wall and 1 sub. My rear speakers are mounted flush in ceiling firing straight down. For best sound and experience, what settings would you recommend, 3.1.2 or 5.1? And why please? Thank you in advance!!