SimCity did a lot of things right, especially the ability to upgrade your facilities rather than having to plop another whole one down like Cities: Skylines demands (apparently this is addressed in the upcoming sequel). And the 'specializations' in SimCity offered much more interesting industrial opportunities to pursue than anything in Cities: Skylines. Also the 'agent' system was used to simulate pressure over distance in the water and sewage systems, which made for interesting challenges in placing your pumps and treatment facilities. I still come back and play it every once in a while :)