None for Katara because, ultimately, she decided to be a healer, mother and not a major player in Republic City.  She headed the White Lotus, she was the one who raised Tenzen, Bumi and Kaya.

Zuko and Aang were the leaders of their nations, Katara was not.  Toph and Sokka were high members of Republic City, Katara was not.  Cabbage Merchant built his own statue.

It was said, word of god, that Katara didn’t participate in the Water Tribe civil war because she felt it was important for other generations to guide the future.

Ultimately?  The real testament of Katara’s legacy is one we see through four seasons.  Korra, who was trained for 10 years by Katara.  

nuff said