Ideally? All of them. First off, every city in Cyrodiil has quite a bit of potential to be interesting if revisited - especially if Bethesda decides to suddenly turn the place back into a jungle, or at least remove some of the more isolated cities from the Imperial infrastructure. I could imagine Cheydinhal falling into the hands of an upstart political ruler from Morrowind, as an example.
Daggerfall could look really interesting on modern tech, and I'm certainly hoping to an extent we get some chaotic and crowded Skyrim cities of this style. If Bethesda utilizes "generic" NPCs as they did with Fallout 3, you could certainly expand the cities a fair bit. Politically, I'd love to see how Gothryd and Aubk-i are doing following the Warp in the West. It's been said in the PGE3 that they're still beloved, although I see plenty of room for some awesome plot involving Sentinel conspirators or something of the sort.
The Imperial City gets my vote. It's the capital of the former Empire and I want to see how it's changed by the time of some future Elder Scrolls game.
I agree. Gee, I feel as if either your views are becoming more and more moderate or I'm getting soft in my not-old age. By the time TES V is released we may merge into one entity! :ahhh: