Most Popular/ Influential D&D

[Zhorn]

By raw numbers, yes, but that seed was planted in fertile ground.

Very much this, but at the same time credit should still be given to the system. The potential was there for 4e also and that did not get that explosive growth 5e got.

4e is pretty much the only edition that didn't successfully redefined "what is D&D" by widely expanding the player base.
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3e's legacy was so popular it overshadowed 4e.
5e is literally the most popular TTRPG ever released.

I'd say currently 3e is more influential, but I'm quite confident that 5e (or an even more successful successor) will eventually overtake it.

For me d&d came onto my radar during the 3e/3.5 era.
I didn't get much into it at the time mostly because finding a group to get properly introduced was very difficult.
Warhammer was the game of choice for the target demographic where I lived, so that's was what I got funnelled towards.
Still, every time I visited a Borders (when they were still here) I'd see a D&D book here or there in the gaming sections (only ever 1 or 2 books buried in the fantasy/gaming sections at a time) and would flick through them now and then, thinking "I'd be keen to learn this if I knew some folks to teach me". First time I got to play was with a group a little too intense for me at the time and so was turned off from picking it up in earnest for a bit.
Xanathar's had just come out when I tried again. I saw the book for sale in a Zing popup and impulse bought it.
Where 3/3.5 had me thinking "I would be interested but need someone to teach me", 5e had me thinking "This is something I could learn and then find/form a group" from that Xanathar's book on it's own.
5e is just so much easier to learn that you can piece most of it together from context.

3/3.5e was good at building loyalty (hence birthing Pathfinder in response to 4e's attempt to move on)
5e brought in the new blood