The Three Body Problem trilogy, in particular the second book. It’s hard to talk about it without giving away the mystery of the first book, but it’s a book series that reshaped my perception of the universe.

Otherwise, there’s Hitchhikers Guide to the Galaxy for some good old British comedy.

The Dispossessed (Anarcho-Communist lunar colony re establishes contact with the rest of the world after 100yrs due to making a huge scientific breakthru) or any other Ursula le guin novel.

xenogenesis series by octavia e. butler. Humans wiped themselves out, horny aliens offer a deal, they restore earth and in exchange humanity interbreeds and merges with the aliens.

House of the scorpion king: drug lords have annexed Mexico and collapsed the us, the king pins live forever using clones for organ harvesting and have a mentally stunted slave class to do the farming. It's a very heartwarming story in my opinion.

Project Hail Mary, by Andy weir who wrote the Martian (also good book). It's hard to describe the book without spoiling it, but essentially slightly more advanced society than ours pools the whole worlds resources to send the protagonist on a one way interstellar mission to discover a way to save earth.

I also just finished the three body problem series, I enjoyed the second book in particular, its beautifully written and well translated but I felt like the series is severely hurt by the authors sexist themes.

Did you just read the first Dune book? If so, I highly suggest getting through God Emperor of Dune. Messiah wraps up (mostly) Paul's story, then Children and GEoD resolve a lot of the themes.

I've been getting into the Culture series by Iain M Banks, which is frequently recommended for good reason.

The Forever War by Joe Haldeman is a classic of hard military sci-fi

Ringworld by Larry Niven is likewise a classic, though I never finished it

Philip K Dick's stories are also a must

Asimov's Foundation series is basically sci-fi's LotR, deeply fundamental to the genre

I know I'm forgetting one or two, I'll add if I remember

The Expanse Series
Enders Game
We are Legion (We are Bob)
Murderbot Chronicles

10 is hard to go off the top of my head, but, in semi-random

The expanse: loved it so much we have our son the middle name Holden

Dune: always a classic for a reason

Children of Time: find myself dwelling on this

Honor Harrington: the best military sci-fi

Forever War: made me think

Hitchhiker's Guide: always makes me laugh (also like Darkside of the sun, but not listing both)

Hyperion: definitive space opera

The matian: definitive hard scifi

The culture: like the federation in star trek, but better.

I don't have much to add beyond what has already been mentioned here but I thought that the Red Rising series was pretty darn compelling.

Blindsight by Peter Watts

The Bobiverse series by Dennis Taylor

Anything by Blake Crouch

William Gibson isn't for everyone but I love him.

Not exactly sci-fi more like litrpg but my favorite series currently is Dungeon Crawler Carl. Audio books are the way to go here, Jeff Hayes is fucking incredible.

I might get shit for this but Project Hail Mary

Andy Weir‘s Books (The Martian and Project Hail Mary) are very good entries and fairly easy to read and brilliant.

Then you can look into Corey’s The Expanse for more „realistic” sci-fi in around earth and/or look into Banks’ The Culture of you want to stretch your imagination.

Further mentions: Hugh Howley (Wool/Silo), Neal Stephenson (Anathem, Seveneves, Snow Crash …)

What everyone said, plus:

Strata by Terry Pratchett

Dahak trilogy by David Webber

Anything by Ray Bradbury

I really enjoy Kim Stanley Robinsons books, the Mars trilogy especially. However a couple of his standalone books are also great (Aurora and 2312).

Also, I love peter f Hamiltons world building. Pandoras Star kicks off a huge story spanning 7 odd books.

And finally, James sa Corey and the expanse series are phenomenal.

A Fire Upon the Deep represent! Now you must read A Deepness in the Sky. Must.

In a spider related vein, Children of Time by Adrian Tchaikovsky, plus pretty much anything else by him. I cried my eyes out about those little spiders.

Snow Crash and Seven Eves by Neil Stephenson

Andy Weir's novels are light and entertaining: Project Hail Mary and The Martian, for example. They're palate cleansers for after the 1984s of literature.

Kindred by Octavia E. Butler is a great read.

Flatland: A Romance of Many Dimensions by Edwin Abbott Abbott is close to sci-fi and from the 1880s. It's a short read and, being a math nerd, I really enjoyed it.

Lots of good suggestions here. I've just ordered Anne Leckie's 'ancillary' trilogy.

I'll recommend Gene Wolfe's Book of the New Sun (The Shadow of the Torturer, The Claw of the Conciliator, The Sword of the Lictor and The Citadel of the Autarch) - Lots of weird, cool imagery and ideas.

I need to get around to The Urth of the New Sun at some point.

Anyone who likes Iain Banks, should give Anne Leckie a try. I've never had that special kind of "Iain Banks feeling" again until I read her books. But Banks is still the GOAT, of course.

Everone always praises Asimov’s Foundation, but I found his robot stories (collected both in “I, Robot” and “The Complete Robot”) more entertaining. While Foundation is more of an adventure story, the robots pose interesting philosophical questions are are always good for a last-minute reveal. They’re also usually quite short, so they’re a good read when your time is on a budget or you’re not an avid reader in general.

I wish I had learned earlier that short stories can also be entertaining and not just the artsy bullshit you’re forced to read in school.

In no particular order:

Forever War. This is a good companion piece and counterpoint to Starship Troopers. As a book I find it more engaging and easy to get through than Starship Troopers. There is a lot of interesting contemplation about society and government structures in the book.

Foundation. A classic novel that tackles the idea of the "great man" theory of history. The next two follow-up books round out a great trilogy. There are more books after that, but those belated sequels don't have the same spark.

Dune. It's Dune.

Hitchhiker's Guide To The Galaxy. This book and the sequels are the funniest scifi out there.

Ender's Game. A great book about a child prodigy in military strategy, and the consequences of a government which uses him.

At The Mountains Of Madness. Humanity is either a joke or a mistake.

Tactics Of Mistake. Decently breezy military scifi. It takes The Art Of War and turns many of its principles into a scifi plot.

Hyperion. Strange, scary, weird.

Old Man's War. Another military scifi that is accessible and easy to get through. Great central concept.

The Moon Is A Harsh Mistress. Robert Heinlein's best book. An uprising, but on the moon.

Stranger in a Strange Land

The Moon is a Harsh Mistress

Both by Heinlein

Anything by Stanislaw Lem. Very philosophical at times, but easy enough to read, and with a lot of jokes and thrills... I'd start with some short storys.

The Stars My Destination was a pretty good one. I don't have a ranked list, but i'll throw in some recommendations anyway.

Allen Dean Foster is one of my favorite authors, wrote many many books set in the universe of the Humanx Commonwealth, although several books work as just stand alone novels with their own things going on. If I had to pick just one: Sentenced to Prism.

Lois McMaster Bujold wrote the Vorkosigan Saga, another series with many books. The main series follows Miles Vorkosigan, who essentially has to spend his entire illustrious career talking his way out of increasingly absurd shenanigans.

Tad Williams wrote Otherland (and other works as well, but I only read the one). It's a single story split apart 3 books, with some good cyberpunk shenanigans.

If you're willing to dip into warhammer 40k, there's some good stories although it's a lower reading level. the Eisenhorn trillogy is a good introduction to the setting, also something of a spy thriller. The Infinite And The Divine is probably my favorite though, features two geriatric immortals harassing each other over thousands of years trying to steal/use a mcguffin, 10/10 shenanigans.

Haven't read 10. I like "a canticle for leibowitz".

In no particular order and I can't order them by preference, so there's more than 10:

Altered Carbon

Expanse, the first two or three

Dune, the first one

Forever War

Pandora's Star and Judas Unchained

The Carpet Makers

Spin

Childhood's End

Ender's Game

Eternity Road

Pushing Ice

Any scifi by John Scalzi is entertaining

The Steerswoman

Vorkosigan Saga

Lots of good stuff from Charles Stross:

• Halting State
• Singularity Sky

Also Vernor Vinge:

• A Fire Upon the Deep
• Rainbows End

A few off the top of my head:

• Old Man's War
• Ender's Game
• Hyperion
• Too Like the Lightning