If this is the type of question I think it is: When Poles speak in Russian. Less rolls of the tongue, and the “l” is always seeming softer. Muscovites as well, because Southern Donetsk Russian has words like “Русского” pronounced as “Russkogo” instead of “Russkovo”. Hearing Czech president speaking in Russian, it was slow and deliberate, but still very good, though he honestly sounded a little more soft sounding than Russian speaker. It don’t know if Romanian counts, but if it does, they sound like Italians when they speak Russian in my opinion. Serbs sound distinct, but not as soft as Poles and Czechs when they speak Russian. Bulgarians are more close to Ukrainians sounding when speaking Russian, and @Sviatogor already covered what Ukrainian sounds like. I have not met people of Belarus (only a Pole whose mum was Belarusian) or any South Slavs West of Serbia or of Warszawa (no Silesians, Sorbs, or Kashubians). I would hope to meet personally a Czech who can speak in Russian, but the one person from Czechia who I know speaks with me in Polish and English. My Czech is horrific, and no one would ever want to hear my accent trying to adapt to Czech (I would outdo Madusa and my voice would turn all to stone).