I'm expecting my first kid soon, and have given this a lot of thought.
We can start with Star Wars and the Clone Wars CGI cartoon (maybe Phatom Menace). They're the most kid friencly, and shows a heroic Anankin, which exactly matches what's said in Star Wars.
When she's a bit older we can watch Empire and Jedi. Once she (shockingly) learns the truth about Vader, we can go back and watch Clones and Sith.