Hello, big city building fan here.
I like city building games because they allow me to be creative. I love fine-tuning my cities' inner workings and to see the complex interaction of a bustling city in full 3D. Cities XL is my favorite city building game because it has nice graphics and I can create beautiful large cities with it. I did not buy the new Sim City because EA really botched the game.
P.S. I am also (very slowly) playing around with my own city building game project. Good luck!