I think it's better to sell everything inside and abandon the cities you conquer.
It's almost impossible to manage them. On my current game I conquest chinese cities and although Im not fighting with their mother country anymore the citizens keep demanding more and more luxuries to forget my "opression". Also, when I start a war against another nation different from the chinese they are the first to go in disorder. The production in AI cities becomes very low when you conquest it. No matter if the size of the city is 25. Soon it will be 15.
So apart from having a city in a strategic place on the map to put your military, or to keep it for a certain resource, is it worth to maintain foreign cities?
It's almost impossible to manage them. On my current game I conquest chinese cities and although Im not fighting with their mother country anymore the citizens keep demanding more and more luxuries to forget my "opression". Also, when I start a war against another nation different from the chinese they are the first to go in disorder. The production in AI cities becomes very low when you conquest it. No matter if the size of the city is 25. Soon it will be 15.
So apart from having a city in a strategic place on the map to put your military, or to keep it for a certain resource, is it worth to maintain foreign cities?