If you are looking for the purest experience:

Steam and other launchers occasionally sold versions (often from the RU/CIS region) that did not contain the standard English voice and text files.

For many players, the pursuit of an "English exclusive" version comes down to a desire for authenticity. Kevin Spacey's performance as Jonathan Irons is a core part of the game's narrative, and hearing it in a dubbed language, or playing with translated subtitles that may lose nuance, can feel like a compromise.