I should have specified ww2 era for only having one example. Considering that unit comes after the pre-dreadnoughts, of which I imagine the Mikasa-esque one is a cultural variant, I would like to see the same with the modern battleships. Bismarck, Yamato, Hood or Nelson, and Roma would all make for great ww2 battleship models without necessarily being a UU.
One of the 'problems' with the Modern Age is that there are far fewer variations available, because fewer and fewer Civs had the capability to build their on.
To take Dreadnaught Battleships and medium tanks for two prime examples, between 1906 and 1945 only 9 countries built any Battleships: Britain, Germany, USA, Russia, France, Austria, Italy, Japan, and Spain. Between 1935 and 1945 only 5 countries built any medium tanks: Britain, Germany, USA, Soviet Union, and Argentina. Using the standard definition of a tank weighing over 20 tons and mounting at least a 75mm gun, neither Japan nor Italy deployed any production medium tanks before their defeat. Australia and Canada both produced medium tanks, but they were largely produced with armament, machinery and designs from Britain or the USA.
Even extending the timeline to the advent of Main Battle Tanks around 1960 (Civ's "Modern Armor" units) only adds France, Switzerland and Sweden to the list: 8 medium tank-capable Civs at a time when, IRL, there were over 100 countries (Civs or IPs) in the world.
And, at least in the designs of Battleships, there isn't that much to choose from. After the initial rather bizaare designs with main turrets offset to either side, they boil down to symmetrical main gun turrets fore an aft, like the British Queen Elizabeth class with 4 2-gun turrets with 15" (375mm) guns or the similar German Bismarck class, or asymmetrical designs, usually with 2 turrets forward and 1 aft with 3 guns each, like the US Iowa and immediately preceding classes, the Japanese Yamato class or the French Jean Bart or Italian Roma classes. That doesn't give a lot of distinctive graphical differences to play with unless you plan to zoom in a lot for the details of superstructures, stacks and masts, and such zooming in and out frankly just gives me a headache after a short time.