Reason, Revenge or Roleplay? How do you decide when to occupy, sack or raze?
Usually, when I take a city, I choose to occupy rather than sack or raze. Logically, this seems like the best option for incorporating a new region into my empire. Sometimes when an AI faction loots or razes one of my cities, I do the same to one of theirs. This is partly revenge - "they put one of yours in the hospital, you put one of theirs in the morgue" - and partly to discourage AI factions from similar attacks in future (I don't know whether this actually affects their behaviour).
Some factions may be better-suited to looting and razing than others. If I remember correctly, in the Grand Campaign the Iceni victory conditions in the Grand Campaig require sacking or razing a number of settlements, and in the Rise of the Republic the Senones can only sack or raze, they can't occupy.
I wonder how other players make the choice between occupying, looting and razing. Do you always occupy, or occupy but take revenge on factions which loot or raze your cities, or roleplay based on the style of warfare of your factions, or do you decide in a different way?