I love city building games, but the one for phone is annoying for me, always contracts, waiting time, collecting money.. and sounds at night when the contract is ready... it is not my type of game on phones.
Between citybuildings games, SimCity one of the best. Awesome 3d graphics, you can see your city in details. But so many IAPs, without them you cant build beautiful city.
Transport tycoon which is open source, but its not exactly a city building game, its more like the building of transport lines in the city. OTTD its called in google play.