The original is great and of course the best one. I do feel the Colin Farrell remake of a few years ago was unfairly underrated, we really quite enjoyed it.
Read the story upon which both films were based: We Can Remember it For You Wholesale, by P. K. Dick. It is easily much better than both movies and has a very different end.
I can't remember the scene exactly but shazza stone gets killed and the female lead says "you used to be married to her?, what a b1tch" and Arnie just sort of acknowledges with a grin and a nod. excellent.