The Diocletian
Fire Fly
Россия and Babylon are both the clear choices? Why Argentina?
Absolutely not. I base my decision toward Argentina on the fact that Babylon was IMO one of the most boring games I ever played in DoC. Argentina is IMO a much more entertaining civ to play. Babylon is essentially a OCC for me, because anything else is subject to three flips, not to mention the Seljuks. OCCs are not fun IMO. (inb4mrrandomplayer)
Russia is a good matchup to Turkey, they both has a large impact on the world, but I feel that Russia's gameplay is inferior to Turkey. Russia is essentially "woo expand west." Nothing stops you from just spamming settlers out there. The only thing that actually threatens you slightly is Mongolia, who can easily be prepared for.
Turkey, on the other hand, has one possible ally in the Mughals, and at spawn is completely surrounded by hostile foes. The only way you're going to get out of Turkey is militarily, and I like that aspect of Turkey's gameplay.