BoiGeorge
Merlin... Slytherin... Now i'm hoping Oz will be a dragon animagus, or a large serpent-related animagus. Heck, it's MERLIN. He might even get to be a Ukrainian Ironbelly! (Anyone who doesn't know, they're the largest species of dragon in the Harry Potter universe. Absolutely massive, and a young one was in one of the movies guarding the Gringotts vaults.)
Honestly he should be in ravenclaw. It's mentioned multiple times that he craves knowledge, and his only ambitions are to protect Nana's orphanage and get his hands on as much knowledge as possible. With this logic Dumbledore should've been in Slytherin too, since he had gigantic ambitions. Not sure if it was something about muggles or eliminating the corruption in the british system or something.