Well, you've mostly left it open, so:
-1984 (excellent dystopia novel)
-Brave New World (An even better dystopia novel, and for me, best novel of all time)
-Commonwealth series by Peter Hamilton (I've only read a bit of one of these novels, but they're reasonably popular, so I'll just throw it out there)
-Doom (as in, the Doom 3 novels are decent and stand on their own. Just ignore the original Doom novel series unless you want to feel as brain dead)
-Dune (I've read only part 1 of book 1 (long story), but the writing is excellent, especially in regards to worldbuilding. I'd highly reccomend giving Dune a shot.)
-Enderverse (The "Ender's Game" universe by Orson Scott Card. The writing style is a bit idiosyncratic, but I thoroughly enjoy them. My advice is to either start with Ender's Game itself, and then branch off into whatever sub-series you prefer within the overall universe)
-Halo (There's lots of tie-in stuff I can reccomend, but the Halo novels, at least the early ones, can be read without any knowledge of the games, so they're worth a shot)
-The Hunger Games (I know, it's popular to hate on YA while praising superheroes for having bows and arrows, but this is still perhaps the strongest YA sci-fi out there, even if it doesn't meet its fantasy counterparts. Reccomend the books, but the films are the better versions IMO)
-Jules Verne (specifically Journey to the Centre of the Earth, War of the Worlds, and 20,000 Leagues Under the Sea. Journey is more fantasy than sci-fi now, due to how our understanding of the Earth's interior has changed, and War is a bit of a dry read, but they still get my stamp of approval)
-The Lost Fleet (Only read the first book. I reccommend it in the sense that it's good, but I don't like it personally. It's military sci-fi through and through, and while well written military sci-fi, military fiction isn't a genre I'm usually into (e.g. Halo is the exception rather than the rule for me)
-The Martian (The novel, not the film. Very well written, good science, and incorporates humor far better than its counterpart)
-Perfect Dark (Similar to Halo in that the tie-in novels can probably be read on their own, and are excellently written by themselves. To the extent that for me personally, the stories/worlds of the novels surpass the games they were based on)
-Saga of Seven Suns (Really on the fence, as I only read the first book. It's space opera to a capital S, with any thought of scientific realism swept aside for grand events that include everything form space elves to space elementals. I...do enjoy the first book overall, but haven't felt the urge to go further. But it might be worth a read)
-2001: A Space Odyssey (Absolutely excellent. While I'm not fond of the film, the novel is absolutely worth a read.)
-Starship Troopers (Only Heinlein novel I've read, but yes, I do reccommend this. Don't expect it to be like the film though, as it's based mainly on discussion and Heinlein putting his ideas forward, but without ever getting preachy with it)
-Star Trek/Star Wars: You'll find some good stuff and bad stuff. 'Nuff said.
-Titan A.E. (As in the novelization. It stands by itself, and is a decent read. It manages to go into drej culture, but the flipside is that a lot of its worldbuilding sets up plot points that'll never be addressed)
-Warhammer 40,000 (See my Star Trek/Star Wars comment)
-Wess'har (Only read the first two books. They're well written, but preacy. VERY preachy. They're the template for Karen Traviss inserting a "mouthpiece character" into every tie-in universe she's worked on. But this being her own universe, it's far less jarring here.)
-Artemis Fowl (I'm stretching this in that these are at least science fantasy, if not full fantasy, not to mention that unlike Harry Potter, these remained a series of children's novels. Still, I had fun with the ones I read.)
-The Homeward Bounders (The only Dianna Wynne Jones novel I read (sorry Howl). It's obstensibly a children's book, but I think it holds up. Characters are good, but it's best in regards to its use of horror. As in, if you think about the full implications of the multiverse it presents, then...yeah. Humanity is boned.)
-Infinity Welcomes Careful Drivers (Absolutely hilarious. It's a novelization of season 1 of Red Dwarf, and stands on its own - I say that because I could read and enjoy it without any knowledge of Red Dwarf at all. You can tell when it starts novelizing the actual episodes by virtue of feeling like short stories, but all in all, this is worth a read.)
-The Transall Saga (Despite its name, this is one book, and sci-fi. Just...sci-fi for very young readers. It gets my reccomendation, but only in that it's great for its audience.)
And the stuff I don't reccomend:
-Divergent (Not a bad book, it's not a knockoff of Hunger Games per se, but it is its disabled cousin)
-The Expanse (I...really don't like these novels, but I'm probably in a minority there. I can say that of the four I've read, each one is better than the ones preceeding it, so if you're like me, you'll at least enjoy Leviathan Wakes)
-Imperial Radch (Only read the first one, can't say I reccommend it for various reasons)
-Snow Crash (...what the fuck did I just read?)
-S.M. Sterling (Really not a fan)
-Moonseed (Okay, it's been ages since I read this, but...yeah. Can't reccomend.)
