There is no jungle to the west but from the tiles which are visible it does not look like there is anything particularly brilliant there either. Settling to the north will cost a little more initially, but this will more than be made up for by the gem mine, so unless there is something like flood plains/gold to the west I think our 3rd city is better off in the north.
Barbarians will start appearing at around the end of the next turn set. If we settle in the north (eg at green cross) warriors will be enough to deal with them until barb axeman appear if we use to warriors for fogbusting as shown in figure one.
If we settle west we will need some better military first and a third warrior to fogbust the eastern half of the island (figure 2). So I still think settling north is the best bet for our third city.
Barbarians will start appearing at around the end of the next turn set. If we settle in the north (eg at green cross) warriors will be enough to deal with them until barb axeman appear if we use to warriors for fogbusting as shown in figure one.
If we settle west we will need some better military first and a third warrior to fogbust the eastern half of the island (figure 2). So I still think settling north is the best bet for our third city.