Which of these 3 slavic languages should i learn?

LOL Lukashenko doesn't speak Belarussian, he speaks Russian only ;-)

Does he?

Romanian is great. I had no problems learning it with Spanish and French as background. But the Slavic elements are very, very few, mostly vocabulary. Romanian shares some elements with other languages in the region (Bulgarian, Greek, Albanian ...) through language contact, it's part of the so called "Balkansprachbund".
But consider that when you travel to Slavic countries you won't be able to figure things out because you know Romanian. You will understand some isolated words, but the grammar is completely different.

Ohh you are a real dump. Why learn such a useless and ugly language as Romanian? It is just a silly Slavicized Romance language. It is pity to your brain to memorize all that vocabulary of a useless language. Have any special reason for it?

Please stop the crap about Romanian when this is a Slavic languages topic.
Go create another topic.