Ah! This one is hard, I love them both pretty much the same. >_<

I liked Russia's English voice a lot more. I mean, his Japanese voice is cutesy and all, but I guess I had trouble fitting it to his character because his appearance is tall and big. (I get that Russia is supposed to have a yandere-esque side to him, and that yandere characters tend to have more childlike voices, but still. xD He's one of the tallest cast members.) I associate higher-pitched/ younger-sounding voices with smaller-framed characters (Like Italy and England). I liked the English dub because Russia sounded mature like an adult, yet it touched in on the childlike 'creepy' edge that was supposed to be the 'yandere' side. I'm not saying that taller and more muscular/big boned characters are supposed to have more mature sounding voices, but that's just what clicks in my head. ;u;

Russia's voice is adorable.

His Japanese voice is my favorite in the whole series.