Assuming your chosen pre-emptive strike is to the chin or jaw, I would be interested in people’s opinions on whether the fist or palm is better. Or the pros and cons of each.
It seems clear that once a physical confrontation is inevitable the single most important physical action is the first attempted strike, probably from the hand, probably to the opponent’s head area, and preferably a pre-emptive strike. It makes sense that you would gain a huge advantage in landing the first solid “head” strike – and you may only get one chance.
It is also often stated that the we should very much limit the number of strikes we should contemplate and train for at the this stage (and in general) because to have a choice could cause hesitation and delay, especially under the effects of adrenalin and fear.
I believe I am right in saying Geoff Thomson favours the fist and W.E. Fairbairn favoured the palm, as I believe Sensei Iain personally preferred in the Bunkai Jutsu book.