Having lived in neither city, I have to go with Milwaukee being easier to navigate for outsiders. It is logical and mostly in grids. It doesn't have streets that lead you in a circle to one way streets going the opposite way that you want to go. If you know where you want to go in Madison and have been there before, it is fine. If you are trying to go somewhere new, you need to consult a map and allow for at least one wrong turn and 30 minutes of extra drive time.