Imagination is what is not perceived through the senses; it is important to everyone so that they might see things from their individual point of view. This is especially the case through pieces of writing.
I do not have a least favourite word. But "stupid," I find is used negatively towards things too often, along with "dumb". I believe negative words like these should not be used too often and be used with care; it could damage the person on the receiving end if used only once.