Well, I'm not sure. Technically it's a three way victory.

The Purge killed the vampire threat and SOLIDER. +1 for terrorist extremists.

The Vampires declared war and destroyed SOLIDER base. +1 for vampires.

The SOLIDER killed a greater vampire threat within the region. +1 for SOLIDER.

That being said, we should consider the dynamics of numbers in the seemingly countless/countable minions each side happens to have.