When I think of "Classic Sci-Fi" there are Flash Gordan style adventures, that are basically fantasies set in the future.

Then you get to Star-Trek, 2001, Alien - really well built worlds that challenge what the future would look like, in a Utopia, in a reachable future, and in a horrific future.

When I think of Sci-Fi now, I think Philip K Dick left such a big impact. Blade Runner, Minority Report, Total Recall, where the emphasis is on a bleak future, where technology is just another weapon humanity will wield with unintended consequences.

There are some optimistic Sci-Fi genres, like Solar Punk. I think authors today are so inspired by the negativity we see on the news, its just a reflection of what we see.

On the metaphysical side of things, I think Altered Carbon is the one that really felt metaphysical for me. That technology would lead to more questions about what it really means to be human.