In no particular order.
1. "The Ember Island Players"
I laughed my ass off every time Toph opened her mouth in this one. I didn't want to believe her when she said that the play was dead-on characterizations but when I was watching the series over from the beginning, I realized Katara was always full of hope and even though the acting was exaggerated in the play, it wasn't wrong. The Katara-Zuko "romance" is also very funny.
2. "Tales of Ba Sing Se"
The Momo dance. I'd leave it at that but Iroh's sweet song to his son breaks my heart and makes me cry. Every time I catch myself singing it, I think of Le Pie and must kiss his face.
3. "Sozin's Comet: Avatar Ang"
It's really Sokka, Suki and Toph's take-down of the fleet that does it for me in this ep. I love how protective Sokka is of Toph and how take-charge he is. And how he grows as a warrior but still sucks as an artist. I also love hearing him say "hair loopies". And Katara finally gets her head out of her fussy britches and returns Ang's love.
4. "The Siege of the North: Part 2"
Zhao eats it. Angry Avatar Ang merges with the Ocean Spirit and saves the Nothern Water Tribe. Great battle scene and I love watching Katara fight and Iroh step away from the tea cup.
5. "The Blind Bandit" & "The Firebending Masters"
A little cheat because I cannot decide b/w the 2. The introduction to Toph really sets the tone for the rest of the season and her individuality stands out. My favorite line in the entire series comes from "The Guru" when she tells her kidnappers, "I'm the greatest earth bender in the world and don't you two dunderheads forget it." And the next episode is about Zuko re-discovering his fire bending and learning the dragon dance. The husband and the Pie do the dance and it is very cute.