Well, popular is really an interesting word, having in its roots "people" and "populace". It is literally true that the cultivars to which the most people have posted are literally the most popular in the database.
Keep in mind: it's not counting photos and comments. It is counting how many individual people have posted a photo and/or comment to each cultivar. Those cultivars that have the most individuals are seen as the most "popular" insofar as the database itself is concerned.
As for the most widely distributed, I don't think we have any way of knowing that. All we can really know is how many people post about them to the site. I would be interested to know that, though. Maybe one day I can correlate the postings with the users' locations and try to find which ones are grown and discussed by the most widely dispersed population.
