What is the most populous planet in the Cosmere?

Question

There are lots of planets in the cosmere. Some of the worlds feel "larger" than others. However, it's not clear which one has the largest population, or how it might compare to the population of Earth at an equivalent technological level.

Roshar seems like a good candidate for the most populous planet, since it seemingly has dozens of countries; on the other hand, they're almost all on one continent. Maybe it's Sel, which has several large empires. It's definitely not Scadrial, where all the population is clustered around one or the other of the poles.

Which planet in the cosmere has the largest population? Since we've seen the planets at different times, let's limit the question to periods we've seen in the books.

Answer 1

In 2015, Sanderson had this to say in answer to this question:

Scadrial is certainly the least populated of the major shard worlds. Then Nalthis, I'd guess, followed by Roshar, and finally Sel--which likely has the largest population. I would have to look closely to see which is bigger between those last two.

And some quotes about population centers:

Kholinar, while not as big as Scadrian population centers, is also large enough that it depends on soulcasters for some of its food. It could survive without them, though, with northern Alethi food production ¹

and

Azimir is larger in population than Kholinar. Kholinar is big by Rosharan standards, but far smaller than an Earth population center (like London) at a comparable time. The warcamps had it beat by a lot--depending on how you view the warcamps. (As one city, or ten small ones.) ¹

and

Azir has a large population density. Cosmere-wise, though, Eldendel is by far the largest. Though I don't have strict population numbers on places like Silverlight ²