When introducing someone to an old title, check to see if there are user-created improvements, such as the complete texture reskin of Deus Ex, or the user-created patch for Anachronox. Small improvements make a world of difference to those who’ve never experienced the universe of a particular IP. I’ve actually been meaning to play through Deus Ex again, myself - the lack of autosave kicks me in the ass every time, but I digress.
To the OP - play the original. Not only have you been missing out on an excellent story and one of the main reasons Valve got to where it did, but you will most certainly not appreciate all the improvements that this mod will bring. I’m not saying to torture yourself by going through it on the hardest difficulty, but I am saying that you will highly benefit from the perspective gained.