I personally believe that movies like Paranormal Activity are more scary than what's above. To me, making the audience think and imagine the horror themselves, as opposed to outright showing it is more psychologically compelling. It's also has a more lasting effect too, since you then carry what you imagined in the theaters back home with you.
But the Exorcist was,..."based on true story". Always thought removing demonic spirits from a human was,.. meh hype. Rather not test it though.