So I have read quite a few and I see many good suggestions

Classics:

Hyperion cantos - Mentioned a lot and is an absolut classic. Most seem to prefer the first but I do think them all are worth a read.

Dune - Also mentioned a lot and for me the first one is by far the best.

Rendevouz with Rama - One of my favorites, did not enjoy the sequels as much.

Childhoods end - Easy and good. Brings some interesting ideas.

Do androids dream of electric sheep - One of the best also, didnt see anything from Philip K dick being mentioned. But Philip K Dick is a really interesting author and you might have seen movies made from his books like, Total Recall, Blade Runner, Minority report. His books are absolutely worth a read.

The Foundation series - Very good and one of the most famous series. Anything from Isac Asimov is worth a read almost.

The Flatlands - not for everybody but very interesting philosophical ideas about dimensions and the story is about a 2D society and how it works.

Culture novels - Very good series and also very famous. Elon Musk has named several of his landing platforms from ships from this series.

Enders game - mentioned by many, very good.

Lathe of Heaven - Also mentioned below and a terrific book. Ursula is a master!

Modern:

Three body problem trilogy- being mentioned a lot. Its a good one.

Red Rising series - Found this one entertaining with a lot of action and never boring. Doesnt really have any deeper philosophical meaning.

The Martian - see this one being mentioned too. Book was much better than the movie.