I've seen a bunch of the people on my Friends list doing it, so I'm going to give it a shot as well. Since I only have eight fics, however, I'm just going to cover the top five. Also, I'm using the hit count from AO3, since that site actually allows you to sort your fics by hit count.
5.
A Voluntary Prisoner (173 hits)
My second fanfic ever and my only true multi-chaptered fic to date, it covers what I think might have happened if the Gaang had accepted Zuko's offer to become their prisoner when he approached them at the Western Air Temple. It was originally written to have just four chapters, but after some discussion with one of my reviewers on FFN, I realized that there were two loose ends that needed to be tied up, so I added an epilogue. Looking at it now, I realize that it shows an extremely idealistic view of how the Gaang might have treated Zuko in that situation.
4.
Problems and Solutions (180 hits)
I don't really have much to say about this one except that it was my very first fanfic and is an expansion of the drabbles found in Chapters 7 and 8 of Kimberly T's drabble series "Avatar Drabbles: Book 4 & Beyond".
3.
Aftermath (192 hits)
This one spun out of my first entry for
avatar-500. The first paragraph is what I entered in the Avatar 500, but I found that the idea continued past that and demanded to be written. It was the first fic of mine that
amanda_violet beta'd and I have to credit her with helping me determine the purpose of the fic. The first draft stopped pretty much right after Iroh told Sokka and Toph about Zuko and Katara's victory, which left it as a generic "reunions and news after the comet" fic. Then Amanda pointed out that I had this great opportunity for Iroh to confront Ozai and the rest of the fic pretty much wrote itself.
2.
Lessons Learned (209 hits)
This was just a silly little thing that spun out of wondering if/when Zuko might tell the rest of the Gaang about how he got his scar, so I'm sort of surprised to see it in second place. It pretty much wrote itself once I realized that Zuko's comment in "The Phoenix King" about being ashamed that he didn't speak out against Ozai's genocidal plan provided the perfect jumping off point for someone to (indirectly and accidentally) ask about the first war meeting he attended. Because seriously, does anyone doubt that the reason Zuko didn't speak out at the second war meeting was because he remembered what had happened the last time he spoke out at one?
1.
A Matter of Trust (269 hits)
I have to admit, I am really very proud of how this fic turned out. Again, some of the credit for that has to go to
amanda_violet, who beta'd it, but I do think that I'm correct when I call this my best work to date. Amanda's main contributions were suggesting the use of flashbacks to relate Hakoda's life to Zuko's and suggesting that I let Hakoda figure out on his own what had happened to Zuko. Given the number of compliments I've gotten for those two aspects, I'm really glad she suggested them.