Yeah Mordru definitely edges out over Amazo as I'm still waiting on the explanation on how he gained the ability to copy magic and other less physical biology based abilities. I mean yeah I know he can do it but unless I'm misinterpreting something his origin says he shouldnt be able to do it. But I think GA Prime would beat Mordru despite being overall weaker 1v1 I think he could take him. Most powerful Mordru was more of a nuke stick and Prime has showed an unusual level of magic resistance for a superman.
Also I'd switch gog for Agent Orange