User blog comment:Weavillain/POLL: Who Do You Think The Most Popular Loud Sibling Is?/@comment-4618045-20170720165125

It's a tough question.

Because there are so many of them and because they each have unique track records, it's hard to agree upon any one in particular. With that said, I'll name a few that I have seen a considerable sect rally around.

Lincoln (of course) has generated a lot of sympathy. Because we spend so much time with him, I think the fandom has a better understanding of what makes him tick than the other characters. Compared to other characters, he doesn't have as many sins/misdeeds and even when he does slip up, fans are more likely to forgive him because they either understand his motive (a benefit of extra screen time) or contend that the grievances imposed onto him by others are enough to make his own wrongdoings negligible (whether or not you agree with that is up to you).

Leni gets a lot of love as well. Fans of her generally agree that she is adorable. She's basically the Pinkie Pie of the bunch just by the sheer fact that she's always smiling and willing to help others out. Even when she gets confused, it's funny or endearing. Outside of the stuff she did alongside her other sisters (as a unit), she hasn't done anything mean-spirited in her own right.

Luna, similar to Leni, is also regarded as a "nice" sister. However in addition to this, Luna is a musician, which is bound to appeal to anyone that enjoys listening to it (other cartoons popular on the Internet have been praised for their soundtracks, so I don't think it's too much of a stretch to presume some fans make that connection). Also, she had been getting more and more love in the last month because she's bisexual. People view that as a vehicle for making the show more progressive (something that other prominent kids cartoons have been doing recently). Fans like that because they believe that Luna's existence is making the show more accepting and making real people on the LGBT spectrum feel good about themselves.

I believe these three are the most popular among fans. While I have heard Luan and Lynn's names get thrown around, I don't believe they have the same numbers. Not to mention that a fair number of fans have been turned off by some of these characters' controversial behavior (a feature the three mentioned above don't have to the same extent).

As for which one of those three are the single most popular, I honestly don't think you're gonna get the definitive answer from this poll. I have seen a number of polls asking this same question and the results vary dramatically because not everyone participates at the same rate. But these are just my observations.