I have the newest directors cut, and it's my favorite. I thought the voice over was hokey, and a little insulting, and I thought the last scene with Deckerd and Rachel that the studio added on destroyed the whole movie. It was a dark movie for two hours, to suddenlly tack on a sunny, happy ending was just wierd.
Also, for the new cut they went back and remastered it, so it's all clear and pretty. Visually, Blade Runner STILL looks good, almost 30 years later. It was the high water mark of in camera special effects. Also I've always thought it was both Ford's and Hauer's best performance's. It takes a lot of attention to watch and get the whole thing, but it's worth it.
But Director's Cut, all the way.