Scholars believe that the main reasons for Vladimir's choice were not really religious. Instead, his reasons are said to be related to economics and power. There were reasons that pushed Vladimir towards the Orthodox Church and reasons that pushed him away from Roman Catholicism.
Kievan Rus had a lot of contact with the Byzantine Empire. They traded with one another and were in relatively close geographical proximity. Because of this, it made sense to Vladimir to maintain close ties with Constantinople. For this purpose, he wanted to marry the sister of the Byzantine emperor. He would only be allowed to do this if he converted to Orthodoxy. Vladimir did so as a way of tying his kingdom closer to the Byzantines.
The other factor was Vladimir's desire to remain free of Roman dominance. He feared that the Roman Catholic Church would try to have too much influence over what happened in Rus. Because of this, he was also pushed away from Rome (in addition to being pulled towards Orthodoxy).