Start at the beginning.
Original 1991 theatrical release first. If you enjoyed that, then treat yourself to the 1993 SE, and if you also liked that, spoil yourself with the *extended SE cut (a home video exclusive), that can be accessed by a code. The code (Judgement Day date) should be provided somewhere on the disc packaging.
- This cut is the same as the 1993 SE version - but with two additional scenes.