Russia

[Unhinged_Loon]

I had little trouble in buying the Turks friendship at the begining of the campaign. They were desperate for a safe border, which suited me fine. Both annoying southerly neighbours declared war on me but to little effect. A few extra units in the nearby town were enough to stop them even approaching.
When Sweeden decalred war, I was able to take St. Petersburg and that was pretty much the end of any credible threat from them....
Maybe I was just extra lucky in my campaign?

[Sheogorath]

The latest patch seems to have improved the Ruskies line infantry a bit, making the 'Russian Rush' approach more plausible. Get into melee ASAP and you can rule pretty much any European line or light infantry. Grenadiers and guard/elite units are a bit more trouble, of course, but you should do alright.

The Russian guards from the Elite Units of the West pack are real bruisers too. I didn't compare their stats with the British elites, but they thrashed a regular British guard unit nicely, plus their uniforms are pretty snazzy :P