Just curious but what would you say is the most popular strain? Im thinking white widow
White widow is certainly one of those strains that is well-known, and its probably one of the most popular.
But getting to a true answer here is going to be tough.
Most people still don't live in states where they can just walk into a store and pick any cannabis they like.
So if they're buying, its typically whatever they can get, not what they select out of a menu.
Part of this is going to be geographically dependent. Like beers or liquor, different types of weed are more popular in different parts of the country. Its part what's available, part tradition/culture.
For example, on the West coast the "Kush" strains are popular. Mexican stuff is "popular" in the Northeast, just because its available. I'd assume the same is true down in Texas near the border. In the middle east and in much of Europe, hash is what's around, so that's what's popular.
In legal places, like dispensaries, or Amsterdam hash houses, you can always ask the proprietor what they sell the most of, but that's only going to tell you what the most popular strains are in that particular shop.