Hard tight fist with proper bone alignment, or a relaxed slapping loose strike? Would I rather get hit with a strike from a hammer or a whip? Which would I rather have in my atemi toolbox, and do I really have to choose.

Phi is hella right, I'd rather touch the wife (mine, Phi, not yours, although I am certain she's lovely) than punch out some Joe. I train for life, not live for training.