Density by Population vs. Density by Area for Ranking Cities?

I feel like this is the kind of question that should have an intuitive answer, but I'm just blanking on it.

I'm trying to compare a bunch of cities by how vegan friendly they are. There isn't good data on what percent of people claim to be vegan, however there is a website that lists vegan and vegetarian restaurants. I am going under the presumption that this is a relatively good way of looking at the demand, and by extension, vegan presence, in a city.

What I'm trying to figure out is how to rank the cities. The most intuitive is to just pick the city with the highest number of listings, but this can be misleading: New York has more vegan restaurants than Portland, but New York is just a bigger city overall. So, ranking by *density* of vegan restaurants is probably more accurate.

But my question is if I should rank them by no. vegan restaurants divided by the total city *population*, or if I should go by vegan restaurants per *sqkm* of the city. Which would better give the result I'm looking for? What would each of them tell me?

The one other question is that at a certain point, the results by density are also misleading. There could be a city that only has 1 vegan restaurant, but outperforms other listings, but only because it's a tiny city, compared to places that are much larger cities that have more than one listing, but still a smaller percentage. How many listings should a city minimally have in order to make the cut so as to avoid this problem?