I think Zod works well for an origin. It's important to show that it isn't the fact he's a Kryptonian that makes him good, Zod displays that perfectly. I love Braniac, but I hate it when he's responsible for the destruction of Krypton like in Johns version or the DCAU (through inaction). It's cheap drama that turns the conflict into simple revenge. I think that in a origin movie there would be a greater temptation to do this, to try and tie everything up, the way they had the Joker be the one who killed the Waynes in 89.