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-5267262-20130116194644/@comment-4721065-20130122064911

Only assuming that you're talking about life with nervous systems, which is an advantage to Reapers (as much as I hate to say it in the light of the anon's points here) and to WH40K Orks, as their spores would be immune. (scroll down below for the detailed discussion). The WH40K Chaos also has many, if not all troops lacking in nervous systems, not to mention the advantage of residing in the Warp, which Forerunners & everyone else cannot access & where they can pull entire planets given enough time, never to be seen again.