The Russians do not like the Russians. They say "Americans/Other EUs better at dota" and also that the EU and US servers are the best ones. It almost doesn't matter where you're located for russians since they have shit net. This is what I was told by many Russians, so yeah. They don't want to play with other Russians because they know they fucking suck. Chinese are almost as bad, it's just, there is more of an emphasis on competition in video games over there so a lot of the obsessive ones get on teams. Americans generally are the most fun to play with if they have good communication skills and aren't from /v/ or /vg/ or aren't, like, 420 smoke weed faggots or some shit.
Also, Utility Characters are the best ones, like Tide/SK/Magnus.