My wishlist would never get fulfilled, I'm afraid. I think I am in the minority in this, but here it is
1) Lots of beta testing and bug squishing. No crashes and nothing like incorrect numbers/data values in the tooltips.
2) Ability to build retaining walls bundled into the terraforming tools. Currently, it's hard to make terraced roads on a hillside without collapsing your buildings.
3) Ability to set grade on major roads/rail as you drag them out. Then if you drag over a small hill, it auto generates a retaining wall to keep your road level, and if you drag over a small valley it fills it in. (No more roller coaster freeways.)
4) It has to be able to handle at least 5 layers of transit in the same tile/space, all laid out at separate times without a million slightly different puzzle pieces to make it work. (Here is what I mean)
Google maps
This has a 4 way intersection, Borean and Pine, built into an overpass, over top of a major freeway. There is also an express lane in a tunnel below that freeway, and there is an off ramp tunnel below the convention center (a building). AND, none of the streets are on a compass grit, they are at weird angles. My absolute biggest dream for Simcity 5 would be to have that much control when planning the traffic.
I want to be able to force bridges, force tunnels, and curved tunnels and make a small bridge pass below a large bridge and draw a road, and then 50 years later stick an el-train above that same road and cross a railroad on one tile, and then dig another road below that exact same tile and basically never run up against a limitation that I can imagine, only to find out that it can't be done.
