I wouldn’t say they’re ‘better’ because everyone has their own opinions. I like them more than the other pairings, though. (I’m still a fan of Katara/Aang, but Maiko is my OTP.) And why I like them a lot … well, there’s a lot of reasons that I’d rather not bore some people with. XD But one of the main reasons is that, they, as cheesy as this may sound, make each other smile. They bring out the best in each other. Mai herself can slap Zuko’s emo ass and straighten him out, despite what others may say. Also contrary to popular belief, Zuko is in love with her. There’s no denying that, no going around it. I thought it was interesting because we were introduced to Zuko’s character as someone mean and angry but when it comes to Mai we see a warmer and sweeter side to him— IMO it makes his character a LOT more likable, too. And in return, he makes Mai happy. What Aang said at the end of the Sozin’s Comet book ‘She’s a lot prettier now that she smiles’ is sweet too, and who makes her smile? I wonder who.
And yeah, I’ll leave it at that. Together they work, together they make each other smile and together they fit.