Personally, I feel that it is a bit more complicated than a simple "A" or "B" choice. There are a lot of factors in play when you are dealing with a potential aggressor, and dealing with these situations takes training beyond that which could be provided in an internet dialogue.
But, having said that, keep in mind that "the hands kill you", not the eyes! Nevertheless, you have to be focused on the bigger picture, to include the person's body language, outside factors (associates of the perp?), eye movements, tone in voice, etc, etc, etc.
To more directly address your exact question, if the perp is coming at you with a weapon, it is really time to stop watching, and start acting!