The different styles of writing you mention are all different genres, and different purposes. I think it would be utterly inappropriate to write on a message board as though you were writing an essay. Of course, you can always change conventions, but it doesn't always work. I guess the question is whether you have something to write about that demands a different genre? I wouldn't say one style or another is necessarily more creative, but I suppose the pieces are different in how one relates to writing.