I didn't answer the question because I think the whole premise on which it is based is simply wrong and that none of the answers are correct.
Koichi Tohei Sensei talks about breathing naturally while throwing. Getting attached to the idea that your stronger on exhaling or inhaling is a weakness that can be exploited in his view. My experience is that you can throw well breathing in, breathing out, etc. as long as your breathing is naturally calm and not from your upper chest.
my 2 cents,