

I probably would not even make a map of the data in the first place. I would just have a bar chart like you drew, because the amount of data is so low, and their geographical position does not offer much additional information or context.
But most of this seems like it is about subjective tastes rather than peer-reviewed studies on what kind of map is more useful.
Funnily enough, I am actually taking a cartography class at uni right now, and a map (on the left) almost like this is in our textbook. The author then showed a redesign (on the right) where he uses columns for representing the statistics as bars instead of numbers.

I’m aware it’s not an exact 1-1 example, but I think you’ll agree that the one on the right is more successful in communicating the differences between states (which I am assuming is the purpose OP’s map as well). This book is as far as I know peer-reviewed and the most authoritative guide on map design in Denmark at least. The author Lars Brodersen is well-respected in his field. According to him, there are certain guidelines when it comes to visual design, that make for better, more useful maps.




There are no country names, only the names of the capital cities, so if what you say is true, the user is required first to know
Especially point one and two are not common knowledge. Most Europeans would not know that Ljubljana is the capital of Slovenia, for instance. It could be easily fixed by changing “cities” to “capitals” in the legend. But I would still argue that the low amount of data does not warrant the map, if the purpose is to compare across cities.
Sidenote: What scholars and textbooks do you use for theory in the US?