My preferred option isn't in the poll - "there could be better choices, but it looks interesting to play" (I voted 1 as the closest option).
Even without the misconception that Venice was "just a city state", as an imperial power it's questionable whether it justifies inclusion in a game like Civ - it was a strictly regional power within Europe, its own culture was of Byzantine origin and it didn't have much uniquely "Venetian' influence beyond carvings of winged lions in occupied cities, and it survived as a city-state much longer than as an empire.
All that having been said, similar things can be said of Sweden and even to a lesser degree Austria, and Venice brings two important things to the table:
Firstly, thematically it's unique. It's a medieval European power, while the vast plethora of European civs in the game are all either ancient/classical, Renaissance or modern in the primary time period they focus on. This is actually a slightly odd omission given the popular interest in Europe's Middle Ages (EDIT: except Denmark - forgot them. Okay, Venice is only the second medieval European power). There's a lot of clamour about which geographical regions to include for civs, but much less about the temporal scope that each region should cover. Aside from Venice, every medieval power in the game except Songhai is Asian or, in the case of Arabia, Mediterranean, and almost all Asian civs are medieval in their main focus (China, Japan, Siam, Korea, Mongolia and now Indonesia - basically everyone except India and the Huns). There should be much more temporal diversity within each region.
Secondly, and above all, it's a very interesting civ in terms of its game mechanics. As a design it's really set up to satisfy both camps - yes, it's an empire, but yes it's also an empire that's based around - and starts from - a single core city that acts rather more like a city-state than like a civ.
Thematically, I wasn't a fan of the Huns, but I like the AI Attila personality and the leader screen is great. There are numerous better civs that could have been chosen than Venice in terms of "importance", but few if any that are better choices for the unique game mechanics it's been given. And that leader screen is astonishing.
