Farming in Empires is somewhat easy because there are so many cities with no soldiers in them and you do not even have to gather intel. Perhaps people played for a while and just abandon the cities. This in a way provides the opportunity to farm safely.
My first choices are players that are not in an alliance.
Just click Profile and focus on ARMY MIGHT. As you could see, it is 0- zero- nada, meaning no soldiers in there.
Just send your army with most load (top right) and exclude the Champion (questipn mark there)
If you are lucky, you would get a lot from the attack. The most important thing is you will get resources without agression.
So if the city is staffed with soldiers, the army might is bigger than zero.
Good luck in farming Empires.