I read Asimov's Foundation series back in the day and "We" by Yevgeny Zamyatin [1921] recently. The latter was a very foundational book for 20th century dystopian sci fi. I also read 'Dirk Gently's Holistic Detective Agency' last month though I am not sure if that would be proper sci fi but Douglas Adams did contribute to the overall genre with his other more famous books.
I have heard praise for "Dune" but haven't read it nor seen it's adaptations[ there was a movie right?]. I think two of my favorite sci fi films are Dark City [released same year as Matrix, I guess, though not as famous] and Fritz Lang's epic Metropolis from 1927.
All I have is praise for the new Dune adaptation. Denis Villeneuve nailed it. And I'll check out the stuff you mentioned, thanks :D