Which is better: JBL Bar 500, Samsung HW-Q600C, or Vizio M-Series?

For most people, the best pick is the Vizio M-Series if you mean one of the surround kits with separate rear speakers, such as the M512a-H6-style setup. It will usually give you the most convincing movie surround experience because it has actual rear channels, and some versions add height effects too.

Pick the JBL Bar 500 if you want a simpler bar-and-subwoofer system with no rear speakers to place or wire. It is a strong choice for bass and a clean setup, and it supports Dolby Atmos processing, but its surround/height effects are virtual rather than coming from physical rear or up-firing rear speakers.

Pick the Samsung HW-Q600C if you want a compact, mainstream 3.1.2 setup, especially if you have a Samsung TV and can use Samsung features like Q-Symphony. It is good for dialogue and general TV/movie use, but out of the box it is less compelling for true surround than a Vizio kit with included rear speakers. It becomes more competitive if you add compatible Samsung rear speakers.

Bottom line: Vizio M-Series surround kit for the most immersive sound; JBL Bar 500 for the best simple bar-plus-sub setup; Samsung HW-Q600C for a compact Samsung-friendly option. The main caveat is that “Vizio M-Series” covers several different models, so the exact model number matters a lot.