Bluesound does not require online registration or an account to use. Some might find that to be valuable.the Sonos has double the wattage output (125w/ch v 60w/ch) for $150 USD less. I don't know if you have any need for that much power.
The only advantage I can see the Bluesound having is Bluetooth AptX HD capability.
In my opinion, MQA or "High Res" streaming is of no practical use to me or any other human beings that I know of. The Sonos can stream lossless 16/44.
Or maybe you got a Bluesound speaker for your kitchen because you liked the sound or features (battery pack) better than Sonos, and you want your living room speakers in the same ecosystem.
Or maybe you just like the velvety plastic and don't care about $150.