Declaration of Friendship expiring

[Sporally]

Killing them off is definitely worse, though by that point, you may have sealed your fate as a warmonger in the world's eyes. Their denunciation's effect on you is determined by their relations with other civs, so the denunciation is probably going to affect less than the entire world.

Great, thanks for that info. Will definitely think about this the next time.

Still didn't get an answer to this question. Anyone out there that could me out here?
Oh, and by the way - when someone denounces me or insults me there's most often an option to bow in front of him or to insult him back ("You'll pay for this" for instance). I've never know what the difference is. Is it only my relation to the one insulting me, or will others react to what I tell him? Which one is better and when?