For me i think it's a forum .
And my reason is not because forums are more complex or any of such but it's a smart way to make money from people's idea which in contrast to creating a blog you do all the thinking, your job in creating a forum is just to step up the plateform. Think about it.

And to buttress my point the more take a look at the leading websites or companies(Facebook, Twitter, Youtube and even Nairaland), have a way of setting up their business that you will fully patronize them in a way that most of their responsibilities are transfered to you and still yet you are happy.