Voice Language: English vs Russian vs Ukranian

I am a huge fan of the Metro series. I love that a rag tag team from Ukraine can put a AAA title together and have it defy all expectations. Even better, the game sidesteps so many western gaming tropes which creates a truly unique experience. Here's my dilemima: I am doing a ranger playthrough of both M:2033 and M:LL and and really want to use the ORIGINAL VO. The studio is from Ukraine so is the Ukranian VO the original? Most people say to play in the Russian VO.....or did the studio know they needed to pander to the US audiences .....so is the English VO the original? All help is appreciated. Super pumped for Metro Exodus!