Wow, what a bunch of cold-hearted despots you all are!
I usually do whatever the General in command would do.
i.e. Chivalric: Release, Dreadful: Execute. If I can't remember which the General is (can be annoying trying to decide and not knowing what your general's stats are) I ransom. I use the same system in capturing cities. Endlessly sacking cities makes the game far too easy anyway :P