Nukes at the very least are not dependable or predictable, two things you very much don't want to depend on in the military world. Only Ares and SK have Thor Shots (and Ares apparently only has

. Bioweapons are a bad idea because the ones that are really effective are viral. And they won't take out any military units. Nanotech isn't self sustaining and is useful on a tactical level, not as a strategic weapon.
System Shock page 80
“The other matter should be obvious. The fault line nukes.
San Andreas was intercepted by an Ares Firewatch unit out of
Silicon Valley. Per protocols, Ares used nerve gas to soften the
target before insertion. Like the other recovered, this was a
conventional nuclear 5-megaton warhead. Despite several
anti-tampering systems, Firewatch successfully deactivated the
detonator. Saeder-Krupp was similarly successful in defusing
the Red Sea device. The reports are in the relevant annexes.
Nonetheless, three warheads were detonated.�
“Your point?� interrupted Anna Villalobos, the voice of
Aztechnology. “We’ve registered massive earthquakes and
aftershocks in Chile and Peru, similar events in India and
Pakistan and the eruption of São Miguel in the Azores … �
“Simply put, assuming the remaining devices were in the
same megaton range as the two intercepted, the effects are far
below any predictions. Not only were the quakes and after-
shocks mostly localized, barely making 8.5 on the Richter
scale, but the eruption in the Azores, massive as it was, was-
n’t followed by tectonic unrest—and no tidal waves!�
“What are you saying, Mr. Steiner?� queried Pirault.
“I’m simply stating facts. I don’t have hard answers, but
all projections for this explosive potential suggested activity at
least as destructive as Ring of Fire flare up in ’61. Instead, seis-
mographs in Antarctica and Moscow barely picked up the
aftershocks. The two devices recovered were conventional
nuclear warheads. We have no reason to believe the others
would be different. You pay me to analyze facts, and what I’m
telling you is the facts don’t add up. Something happened.
Winternight should have succeeded. And this is not the first
time since the Awakening that we’ve seen nuclear detonations
that were inexplicably ... limited. In fact, there seems to be
abundant evidence that large-scale nuclear detonations are
simply no longer possible. If there are forces in the world with
the capacity to—�
Thank you for your warning, Mr. Steiner,� Pirault
forcibly cut him off. “Rest assured it will be taken to heart and
the Court will look into this, at a later date. Our priority now
can only be damage control and recovery. Now, if you will
excuse us, we have urgent business to attend to. I believe,
Miss Osborne, that the next item on our agenda is Transys-
Erika’s proposal ... �
Steiner nodded, realizing he was dismissed. He shoved
his notes into his suitcase and proceeded to the airlock, fight-
ing the temptation to look back. He could feel Pirault’s eyes
still on him, and he wondered not for the first time what the
Frenchman knows that he isn’t telling ...
As for who actually wins, it depends on what Corps back what countries. And thats only if the Corps were stupid enough to not step in and end it before all out war enveloped a 7th of the world (also known as a huge customer base).