Im sorry. Sci Fi and horror are my least favorite genres.

Enders Saga by Orson Scott Card. Not personally read the series but watch the Enders Game movie to see if you like the 'Universe' it makes, and if it catches your intrigue the give the Saga of books a go. Of course its the classic 'the book is way better' pinch of salt you need to take when you watch the movie (its alright... just alright, but in my mind the story has a lot of potential).

The expanse series!

Everything by Stanislaw Lem.

idk, when I was young I used to read sci-fi and for some reason I liked Ben Bova. Not that I think I had exposure to a lot of different authors. I also read some Isaac Asimov, though I remember finding one of his stories to be very unrealistic which I thought was dumb. And of course the best sci-book ever is HHGTTG, but I'm sure you've read that. =)

Need more context what type of sci Fi?