Necrosword vs Gungnir vs Mjolnir vs power ring (volthoom)

Which would you rather have? And which do you believe is the most powerful?

Gungnir doesn't do anything, so that's out.

The Necrosword is pretty awesome, and probably grants a the most power.

Necrosword seems to give both the biggest amp and the ability to create living constructs puts it up there with the ring in versatility.