I feel like Toph should be the other way around
In order of best disguise to least:
Appa
Aang
Sokka
Momo
Zuko
The girls all last place because none of them are truly disguised.
Katara put on a hat and a veil with some squiggly face paint. Suki did the opposite and took off her makeup. Toph did her bangs.
The boys have sweet new facial hair and epic costumes. I rest my case.
Wang Fire has to be first place. And I love Momo’s hat, I only noticed it for the first time recently - it’s from the Fire Temple episode, Winter Solstice, Part 2: Avatar Roku.
Some of these aren’t disguises though, just outfit changes!