You don't want to be buying a dead-on-arrival device! Know your requirements first by checking your existing setup and what you want to use the sound system for.
Underlying all the audio setups above, you clearly have to check what ports your TV supports. While it's safe to say that most have HDMI, you may want to check if there is a 3.5mm line-out or an optical jack. A few TV manufacturers make it a point to do away with what they deem unnecessary to sell TVs at a lower price point.
If you want to stream from Spotify or Deezer on your smartphone, minimally get a speaker system with Bluetooth connectivity. It helps loads if you want to use the system even when your TV is switched off.