Any particular reasons why?
The "best" reaction seems extremely relative, whatever may trigger it. Would vary according to one's objectives and values and the parties involved.
In sales it can be beneficial to be overly apologetic. "Oh, you did (insert incredibly stupid mistake) and you (insert product) (broke/died)? I'm terribly sorry, here, have another one on me!" Because clients can be stupid and bad publicity, no matter how unjustified, spreads more than good publicity. Is this the best reaction? Maybe. Different people have different tolerances of kissing ass.