I still don't see how AM would win.
Remember there was another CoIE AM thread and some one brought Death of the Endless into the discussion? Majority of the people agreed that Death of the Endless would beat CoIE AM (or at least be immune to anything CoIE AM did making it a stalemate).
I don't see why Nekron would do worse than Her. Nekron isn't merely an aspect of Death. On panel he was described as the "darkness before Creation" AND "the space between atoms". So it's like he's a hybrid Death/Oblivion abstract being.
So it's either a stalemate or Nekron wins.