Do you prefer voice overs or narrative structure?

From researching existing trailers, we realised that some used a voice over and some used a narrative and some used both. The voice over is spoken over footage of the film, and gives the audience a slight indication as to what the film is about. A narrative is when the audience are given an indication as to what the film is about through 'snipets' of the film being shown and characters giving away the story's main synopsis through dialogue.
As we are making a teaser trailer, we found it a good idea to ask whether people preferred narrative, voice over or if they would like both. The results show that 75% of the people asked would like to see both narrative and voice over in a trailer and so this will be incorporated into our trailer.