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-50.80.96.33-20130111215612/@comment-2250460-20130111222507

We don't even know if Indoctrination would work on Forerunners or the IoM (by the way, the IOM are stronger than the Forerunners i believe).

Secondly, multiplayer isn't canon, so you can't use retaliation as a source for the Collectors. If you have a source, please present it, otherwise the Collectors and the Flood are not part of this War.

This war is between the IoM and the Forerunners, and I would think that the IoM would be the victors here.