This is all interesting, but also kind of confusing. Different ways of measuring the data produce different results. (We have a word for that in engineering.)
According to D&D Beyond, which measures the sheer number of characters created on their own platform, Fighter is the most popular class. So among people who use D&D Beyond, the Fighter is clearly the king.
The new Baldur's Gate 3 video game shows the Bard Paladin to be the most popular character class. So at least among players of that one video game, Bard Paladin is supreme.
That Zippa article, which counts the number of states where a particular class is the favorite Google search, Monk is the most popular class (since it's the favorite in 19 states.) And Wizard, the favorite punching bag of ENWorld, supposedly responsible for making the martial classes "useless" and "obsolete," is the favorite in only a single state (Utah). Bards haven't won any.
D&D By State Research Summary Utah plays the most D&D in the US, followed by Idaho, Oregon, Maine, and Vermont. New York plays the least D&D in the US, followed by New Jersey, Mississippi, Georgia, California. Monks are the most popular class, being favored by 19 states. Ranger and Druid tie for...
Frustratingly, it also doesn't list its sources. It does "show its work," so to speak.
It also says that the three states with the least D&D are:
50. South Carolina
The article I linked in this post puts the number of people actually playing at 13.7 million.
I'm not really sure. I'm looking for better info but so far, nothing. If you find something, definitely post it.
The article says, "To determine classes, we used the 15 most common D&D classes and did a similar analysis of Google Search Trends."
First, what do they mean by fifteen most common classes? Last time I checked, there were only 13.
Second, until we know exactly what those Google search terms were...well, I guess the map is as true as you want it to be. Were they Googling "Optimized Monk Build 5E", "5E Monk Table Roll20", and "Monk 5E Subclasses"? Or were they searching "Why Monks Stink," "How To Fix Monk", or "Monk ENWorld"?
I imagine folks who hate Monks will insist the searches resembled the latter category...
So what they determined was what class people Googled, and people don't Google classes they understand well nearly as much as other ones. I can see that just looking at my own Google results, for example. "Searched for" does not equal "Popularity" it equals searched for.
I'd also like to see exactly what qualifiers they had to ensure people were search on the actual D&D classes, not on, y'know, monks in general.