Zuko is my favorite character, so I'm Zutara :D Did you guys know that the creators made a comic series of what happened after the show ended? Well, I read the comics and Mai broke up with Zuko!!! So now Zutara could totally happen :D
I know that Katara ended up with Aang, but I think her and Zuko would make a better couple... Like Mai and Zuko's negativity just cancel each other out, and it's a dull relationship, if that makes sense.
I feel like if Ty Lee was closer to Aang's age, they'd be perfect together.
Totally Zuko. They even have like one hint of their "love" in the episode where they were in the crystal cave. When they show Katara and Zuko fighting from a birds eye view their bending elements(water and fire) kind of look like hearts. ZUTARA FOREVER!!!