I think the best arch-villain for Namor should be someone that be seen as a real threat, I love the Squadron Supreme as a Roxxon Company super team and as Namor's arch enemies, just makes sense but none of that nonsense of Hyperion being a superhero or him being able to kill Namor. Allright he did it once and the resolution from that was handled terrible. I want to see a re-match, make Hyperion Namor's Doomsday but let Namor outsmart him and claim victory. Otherwise the three you have named are the best ones but they need to be written well as they were in the silver age. I also like Krang and Byrrah. And I would dust off Piranha, Orka and She-Devil and make them really dangerous and psychotic.