Warhammer's 40K Primarchs get DC Power Rings of their choice. Who ends up the strongest among them?

The 18 Primarchs, at the start of the Horus Heresy, each get a DC Power Ring ( Green Lantern, Yellow Lantern and so on ) which best suits them. For instance, Angron would certainly fit the Red Ring of Wrath/Anger the best, and Konrad Curze would fit the Yellow Ring/Fear.

Who becomes the strongest among them?