As a native from Umbria (and with a passion for local history) I would say that there the obvious option would be Perugia, which already controlled large swathes of territory as far as the lake Trasimeno and beyond. The problem is, many smaller cities preferred a (relatively loose) papal overlordship over a tighter control from a nearer city. A clear example of this is my hometown, Assisi. After losing the war with Perugia in the early 1320s,, most of its city walls were razed to the ground, effectively reducing part to the city to the status of "contado". The walls were later rebuilt around 1377, when the Cardinal de Albornoz restored the papal control over the city, thus effectively being perceived as a liberator. There is also the problem of dealing with the internal divisions in each "comune", with almost every city being divided between "Guelfi" and "Ghibellini", now mere labels (as Perugia, the most "Guelf" of the cities, was the first to raise the banner of rebellion against the Pope when he tried to regain control of the papal states while planning its return to Rome) but which made realistically closely impossible to assert a long-lasting independence.