Now, we all have our preferences on fan-based relationships. There is the strong flow of possibilities,
Katara and Zuko, Zuko and Mai, Katara and Aang, Sokka and Suki, or Sokka and Toph.
I personally prefer Katara and Aang over Katara and Zuko. One, Katara hates Zuko for almost the entire series, while Katara and Aang have this "they love each other and everybody knows it except them" thing going on, which I think is absolutely adorable. Katara feels somewhat motherly to him, very overprotective, but she also has this slight crush on him.
Zuko and Mai are very cute together, and they have almost the some personalities, especially shown in season 3. I think that's that makes them so compatible. Plus, it would be very hard for Katara to switch from absolutely hating him to loving him beyond belief. I know some people can go from mad at you one minute to okay with you the next, but to go from hating someone for 6+ years to loving them like they're married, or something.
Sokka and Suki are the same age, and they both just have a certain connection that makes them so adorable together. Toph and Sokka are so witty and funny and sarcastic, but there is a slight age gap. It seems to me as if Sokka takes to Toph as a bigger brother, instead of a lover. And, let's all admit it, it would be very weird to date your younger sister.
Azula: As Iroh said in season 2, "She's crazy and she needs to go down." I cannot see Azula with anyone because she, being the crazy person she is in seasons 2&3, she would be waaaaay high maintenance. Plus, it would be very hard to marry someone while they were in prison.
Ty Lee: I see her as the independent type because she is very free and solo. And even if she did get married, we all know she would teach her kids to be free and unique like she was, because she said she joined the circus because "she was afraid of spending the rest of her life as a part of a matched set". plus, she would most likely teach her children to be human spidermonkeys, like her.
That's my opinion! Byeeee!