The difference I find comes down to quality of sound. Most sound bars are very limited with small drivers which really can't give a nice full midrange and upper bass above the sub. I had the ARC and have installed many. I like the Sonos architecture and we use Sonos a lot at work. I like it much better than Denon Heos, Yamaha Multicast, Bluesound and definitely better than Play-fi but some of the others have merit depending on the system. The ARC simply didn't compete with my pair of bookshelf speakers which flank the TV. The bookshelf speakers are Paradigm shift A2 active speakers with 5 1/4 woofers and built in DSP, but I do throw in the Genelec G4s or JBL 308s in the TV room sometime and they are both definitely better than the Paradigms and my family all preferred them over the ARC and any other sound bar so far. Some sound bars I have had here I feel are better sounding than the ARC but have not compared side by side.
We have done a lot of comparison with sound bars at my house and we still keep coming back to the speakers. One thing I find with using speakers for TV is to not place the speakers too far apart. Placing them further apart has some benefit for music but not for TV as it narrows the sweet spot too much. The speakers are only about 6 feet apart and the seating is 9-112 feet away depending where you are sitting on the sectional couch. I do have a Sonos port connected to it as well for listening to music. I use a signal sensing switcher to keep things simple. But, YMMV on what you prefer.
We have done a lot of comparison with sound bars at my house and we still keep coming back to the speakers. One thing I find with using speakers for TV is to not place the speakers too far apart. Placing them further apart has some benefit for music but not for TV as it narrows the sweet spot too much. The speakers are only about 6 feet apart and the seating is 9-112 feet away depending where you are sitting on the sectional couch. I do have a Sonos port connected to it as well for listening to music. I use a signal sensing switcher to keep things simple. But, YMMV on what you prefer.