I've heard all this before and have a million and one ways to not only prove you wrong but can counter it, but I've grown weary of this topic with people like you who refuse to accept the truth. Shipper denial I believe it's called. But I was formerly a Kataanger myself all the way through when I was younger, and a hardcore one at that, so I get it. It wasn't until I got older, got a better understanding of relationships, people, writing, and storytelling that, after watching the series again, saw that Zutara worked so much better, and what all the Zutara shippers were talking about and how it was not only so much better, but also how much Kataang fell short (but if that's what does it for you, cool). Yes, Zutara didn't happen, but it very, very, VERY easily could have. All the groundwork was there. The only reason it didn't was because the writers said no since they wanted to go with the "hero gets girl" trope. It's even been argued that Kataang was just a self-insert from Mike and Bryan since they both said that they based Katara off of girls they liked but didn't get with in high school, and since Mike looks just like adult Aang. And again, Bryke, the executive producer of the series even said Kataang felt forced and rushed, and the voice actors for Katara and Zuko who personify the characters were for Zutara. Writers make bad calls or the lesser of two good calls all the times, the number of bad or ruined franchises show this.
Katara gave little to no interest in Aang. Their relationship was basically mother/son, brother/sister. Yes, Aang had a crush on her, but we didn't really see anything from Katara's end. There were only 4 instances in the entire series. When she acknowledge that Aang was a powerful bender after Aunt Wu's prediction, when they supposedly kissed at the Cave of Two Lovers, when Aang kissed her before the invasion (after which she frowned and looked away), and their dance in the Fire Nation school. And after each and every instance, they're relationship went right back to the way it was before, as if nothing happened between them at all. Then during the last 30 seconds of the final episode, she's suddenly completely in love. Honestly, it would have been better if they ended the series shipless and just revealed that they got together in LoK. That would have been more realistic than pretending that the barely seen love story between a 12 year old and 14 year old that was primarily a mother/son brother /sister relations was an epic love story.
And speaking of LoK, we saw how poorly the Kataang family ended up being. Aang was a horrible father who greatly neglected Bumi and Kya while openly favoring Tenzin to the point that the siblings all became resentful of each other and of Aang. Plus, he was always leaving for Avatar duties. And Katara never spoke up about what Aang was doing to their family because she was always mothering and babying him and trying to keep him happy over what was important just like she did in ATLA, which also caused their kids to resent her a bit as well for not doing anything. Had Aang had someone who was more suitable to him, like Toph or something, they would give him the wakeup call he needed rather than what he wanted all the time, and it would have solved so much. Katara was such second fiddle to Aang that she didn't get a fraction of the recognition the rest of the GAang did, not even a statue, especially since she defeated Azula. She also completely changed as a person who loved going out and helping the world to a stay at home mom who became best known for being a great healer (something she literally fought the stereotype of). I could go on with numerous other drawbacks, but there's your Kataang happily ever after. A dysfunctional family with much resentment between kids and parents, much of which can be chalked up to Aang being a bad parent and him and Katara being mismatched. Oh, I'm not saying they were miserable or not happy, but they had a LOT of problems, many, if not most, can be traced back to why Kataang doesn't work as well as Zutara (please note that I said as well, not that it doesn't work).
Zuko and Katara though had the biggest connection out of anyone. They understood and related to each other more than anyone else, even Aang, and had the closest relationship. True, it didn't take a romantic turn, but it easily could have. And because of their compatibility and relatability, they would have had a much better relationship and not had many of the problems that the Kataang did. Their own problems, sure, but not as bad as Kataang.
I could go on with the many other ways Zutara works better than Kataang, but I'm getting a headache, so I'll close it with this last stuff. The links to those videos do a much better job explaining and providing evidence than I do, so you can just watch them and see what I mean (until you actually listen watch those videos, you'll only ever be all talk). But I'm going to guess you won't and will continue to bury your head in the sand and scream that Kataang is more popular when it's not. And provided the most popular media. Ha! You mean you SAID you saw them on the most popular media, videos, pics, etc, yet provided nothing, where I actually provided the results of the actual most popular art, stories, talks, videos, etc. And you cling to your one poll where Kataang won, forgetting just how big the internet really is, where Zutara drastically dominates polls in other areas (the ones I linked are just small examples since I stupidly didn't save the links, only the results). Not to mention the 33 poll results I posted that had just as many, if not more votes as the 200,000 you claim yours has. But even if that one is true and does have the most, that's still just one poll you're clinging to like a life preserver while ignoring the many others that Zutara dominates. And polls aside, you only have to actually look and you'll see how Zutara is the more popular. Again, Zutara carries the "fan-preferred couple trope". It doesn't get that trope for being less popular than it's rival.
Even when I was a hardcore Kataanger, I still very reluctantly admitted that Zutara was definitely the more popular of the two. It's sad that you can't even bring yourself to accept that much, but I found that this is the core to a lot of those toxic Kataangers' anger and lashing out, because they're pissed that even though Kataang is canon, Zutara remains more popular,which they can't stand since they wanted Zutara to fade away after Kataang became canon, but it had only remained strong and only grown in popularity. And again, Zutara is fighting against the Kataangers, the Anti-Zutarians, the canon purists, and the non-shippers who just pick what's canon, and it's still more popular. But hey, maybe one day you'll find yourself doing a 180 as well. Honestly, I don't care. Kataang is canon, Zutara is more popular, however you feel about either ship is irrelevant and subjective.