Really depends what you want in a system, and what you want in exclusives. I think Xbone is a better all around entertainment hub for movies, music and gaming + the interface looks better than PS4. However if it is pure gaming it could also really depend on what you want i.e. JRPGs, Unchartered, Gran Turismo, Infamous, the Crew etc or Halo, Forza, Titanfall (1), Sunset O/drive type games.
I currently have both, and have not used my PS4 since boxing day, as the Xbone also serves for streaming content from PC as well as gaming. PS+ is great, however Games with Gold just started for Xbone in June so it is really a preference decision.