Hi there! The best choice is an Ultra High Speed HDMI (HDMI 2.1) cable.
This type of cable fully supports eARC, which is required to pass lossless Dolby Atmos audio from your TV to the soundbar. You don’t need an expensive brand, just look for an HDMI cable that is “Ultra High Speed Certified.” If your cable run is short, any certified HDMI 2.1 cable will work perfectly.
~ Samsung Solutions