I'm not going to vote, as my opinion doesn't really fit into any of those. I like the idea of a narrator, but I think it needs a tinkering.
I'd like to have the narrator state the desired plots, with the general information given, and let the members take it from there. But if things get too off-track from the point they're trying to say, the narrator has to intervene a bit I guess.
And, as a compromise for those who don't like it, when you get the turn to be narrator, you have the option to make it spontaneous if you like.