Artifacts in Heroes III.

Question: The best artifact in the game is probably the "Helm of Heavenly Enlightenment" (+6 to all skills), but I'm not sure. What artifact do you think is the best? For example, sometimes you get more joy from "Boots of Swiftness" or "Wings of the Angel" at the beginning of the game. A composite artifact, "Alliance of Angels," is probably the best. Although, for Necromancers, the "Shroud of the Dead King" is better.