Flat vs. Angle sleeping

Danielle
Trying to decide if we want to use a bassinet for the first couple of months or a rock n play. I was always told newborns should sleep flat on their backs unless they have acid reflux, then to have them at a slight angle. I've heard good things about the rock n play just not sure if that's where a baby should be sleeping through the night. With my daughter I used a bassinet and she was perfectly fine, no issues! Just looking for some advice! Should the baby be flat or angled? Or does it matter? Thanks ladies 😊