"One with better audio than the OP has now" is very subjective. Surround sound gives better home cinema experience for some (in which case the OP needs to look at adding rear speakers). If sound upgrade, in what way is the sound lacking in the current setup?
A separates system will usually be superior to a soundbar, although in your case if Atmos works well with your ceilings, you may find better experience with Sonos Arc. Sonos Arc will limit the number of sources you can add as compared to an AV receiver. Depending on which TV you have and your source, you're unlikely to get uncompressed HD audio with the Arc.