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Legend
Evidence points toward the fighter being very popular.Do they? Do "a lot" of people feel that way. I've seen no evidence of that. Indeed I think it's one of the most popular classes as it is right now and an overwhelming majority do not think it needs to be fixed or improved or changed in any meaningful way. Is there evidence suggesting I am incorrect?
DNDBeyond has the only large sample data that I'm aware of. The problem with the DNDBeyond data on classes is that "Characters with multiple classes count once for each class." In other words, it doesn't differentiate between a fighter 1/wizard 9, a fighter 2/ranger 8, a fighter 10, and a wizard 10 – those would be tallied as fighter = 3 active characters; wizard = 2 active characters; ranger = 1 active character. So when they say that 13,906 active characters are fighters, we don't know if that means they have a two-level dip in fighter to get Action Surge as part of a build (for example) or if they're dyed-in-the-wool single-class fighters. So, yes, you can say "fighters are the most popular class" and technically that's true, but there's the outside chance that it's obfuscating what is really going on.
I recall a D&D Survey in April 2016 which asked (paraphrasing) "which areas of D&D do you think need expansion?" Supporting the DNDBeyond data, they found that the fighter was the top class in terms of use in play. Don't know how many respondents were involved, but people wanted firstly more feats, and secondly more character classes. The classes that players wanted to see expansion for the most were (1) ranger, (2) sorcerer and druid, (3) fighter and warlock, (4) barbarian, bard, monk, paladin, rogue, and (5) very few wanted expansions for cleric or wizard.
There's also small polls (hundreds of respondents, not thousands) on various sites, which, obviously, we should take with a grain of salt. DNDBeyond has one with 363 respondents, where they asked for favorite two classes, and fighter was middle of the pack. I also presented a poll on ENWorld in July 2016 (site crash wiped data), asking "Does the 5e fighter accommodate your play style?" Out of 505 respondents, 63.2% answered "Yes, the 5e fighter accommodates my play style nicely. I like it alot." 18.6% answered "Not really - my preferred fighter is in 4e (or 13th Age)." 12.7% answered "Kinda sorta, but it's not a big deal. Good enough." And very small percentages selected "Other" or "AD&D fighter" or "BD&D fighter" or "3e fighter."
People like myself who'd be interested in seeing the fighter redesigned definitely do not represent gamers as a whole in this regard.