The safest one, but considering that you have two types of devices one of which is, obviously, more reliable in terms of distance-to-obstacle evaluation, the threshold for the less reliable system (cameras) may be more tolerant to "probably an obstacle in front of the car" situations. But it's just speculation, the most valuable feedback comes from the users of both systems, and this feedback disappoints.One signal tells you A, the other signal tells you B which do you believe? If its the safest outcome then you still get phantom breaking. If not ...