I don't know how many of you already have this or even heard of it, but Cities: Skylines is a new city builder from Paradox and Colossal Order. It is pretty much everything SimCity should be, just without all the unnecessary fluff, bloat, and general idiocy.
Maps start out at 4km2, but can be expanded up to 36km2 with new additions after various population increases. Traffic is realistically presented and can be a pain to properly figure, as there will be congestion and high traffic areas as your industry builds. Pretty much any major city will have those same issues, and Cities presents it in one of the best ways of late. You can set up different districts, so you can turn an industry zone into one focused on farming or oil mining; or issue tax reliefs/increases to certain ones and not others; or turn a commercial zone into small business-friendly; or curb power usage in one; and so on and so forth.
Oh, and Cities: Skylines has mod support. There are mods to add all sorts of things, even to expand the max size from 36km2 to 100km2. Paradox does offer a hard mode mod to make things cost a bit more and make money a little tougher to come by, so if you're swimming in dough in one city, turn on hard mode. There's also an asset manager to design your own items to put in the game and/or offer on Steam Workshop, plus a map editor to make your own terrains to build in.
You can pick up Cities: Skylines for $30 or $40 for the Deluxe Edition (adds in five wonders, soundtrack, and art book). Green Man Gaming offers both at a discount through the VIP section, if you want to save a little dough.