I get where you're coming. It didn't blow me away on my first viewing either. But, it just became a film that I kept going back to watch. Especially after I watched the Director's cut, which is far superior. And now it's definitely one of my favourites. In terms of the sci-fi films you referenced, it's not really on the same level.
The story is about the characters and the world, rather than the events surrounding the plot. In particular, the character of 'Roy' played Rutger Hauer, who for me, steals the show from Harrison.
But hey, different strokes different folks... Aliens is also a cracking film though!
Thanks for the reply. Aliens is really more of an action film, but the color and style are a little similar. I think I was probably reminded more of Logan's Run than anything else by Blade Runner.