Without prep I don't think Doom and Vril are going to be much help. Terrax vs Atrocitus would probably be an epic fight. I think people really underestimate Terrax because of how Sentry punked him but he's really formidable and has given other Herald level characters
Ultimately it comes down between Thanos and Darkseid and that's been done to death, I think Thanos vs an Avatar could go either way, but DCNU Darkseid as far as I know doesn't have showings like his pre 52 version did where he was struggling with Superman/Orion characters.