I would recommend City over Kuring-gai if you have the UAI. There are a lot more shops and things to do in the City. Also, there are a lot more students doing it at the City, hence more class options. Some of the subjects are only offered in certain semesters at Kuring-gai while in the City they are usually offered every semester, hence more flexibility in your degree. Also, some of the less popular majors aren't even offered at Kuring-gai for which you might have to come down to the City to do anyways.
Hope this helps!