SF usually is shit.
I guess it's just what Philippe Muray used to say: "The Unreal has become a social command".
We hate this 'harsh' Real world, so we wish to escape it and dream.
I believe the best literature is the one in which the author tells us what they have to say about Life's problems and those who wanna live in a "fantasy world of childish banalities" (to paraphrase Sir Alec Guinness).
And that's what the greatest authors did: Dickens, Goethe, Hugo, Dostoevsky, etc.
I like SF fictions when they are dystopias like Orwell's 198
4 (which wasn't meant to be SF by the way) or Huxley's Brave New World
. Great works to denounce this shit Progress teleology.
Or in cinema, Abel Gance's La fin du monde
is a masterpiece.
I also rather enjoyed the Back to the Future trilogy because it was still connected to the real world but how the world of 2015 was depicted is shit. I mean it's two years and one month from now and I still don't see hooverboards or flying cars.