User blog comment:James12708/Reapers VS. Forerunners VS. Angels from Darksiders VS. Humanity from Halo VS. Council and humanity from Mass Effect VS. Imperium of Man/@comment-3145523-20121117003327

Too many sides!!! and 1/3 of them I don't know anything about.

I'd say:
 * Forerunners can beat everyone especially the Reapers, unless Commander Shepard and Master Chief do something about that.
 * Halo Humanity wins over Mass Effect Citadel and Humanity

Commander Shepard vs. Master Chief
 * As a Fighter: John-117
 * As a Leader: Shepard