As an outsider with no real knowledge of what's happening beyond that there is a war and you guys like to fight a lot: I have to say my virtual, imaginary money is on the Prussian side. For two reasons, mainly. One, Prussia's history of ass-kicking in war is well-known. Two, Russia. They have a lot of people to throw at the opposing side.

Austria's side does have the UK, though, which means they own the seas. Greece is especially fucked given how the Ottomans and Austrians probably own the Mediterranean and definitely the Adriatic (unless the Italians can match them, which I doubt). Not to mention whatever support the UK can lend.

It's actually a pretty even match, to be honest. But Russia's population is TOO DAMN HIGH.