I find it helps to consider the attraction of Zutara from a chemistry stand point: Katara is Zuko's true rival in bending, they have similar temperaments, and Aang is very much the Kid to most of fandom.

Aang and Katara mesh to well too interest me in their dynamics. And I agree with you with the destinied love trope is well overplayed. I prefer my starcrossed lovers to have to work for their happy endings if they can get them at all. Fated love is too often a shortcut for things like actual character development.

I much prefer the worldbulding or AUs like Katara being rescued and raised in the Fire Nation by Iroh. Tempest in A Teapot by Akavertigo.