Okay, let me see. I read a lot of sci-fi. And not all of it is ancient.
-First off, Andy Weir's The Martian. Everyone knows this book is great. And it is. What you may not be aware of is the philosophical short story he wrote before The Martian, The Egg, which is also excellent. Weir does have his weaknesses (his next book was pretty universally panned for a lot of reasons), but these really do show him at his best (which is to say, approximately 40 million times more deserving of your attention than Ernest Cline -- no, bad Thoth, stay positive). The other thing that he's known for is "and Bob was there too" which is pretty funny in my opinion, but not sci-fi.
-In slightly less known territory, Cory Doctorow. I read a significant percentage of his novel in elementary and middle school (without paying a cent -- thank you Cory!). Most of his older books are still free downloads, for the cash-strapped. If you like rebellions, activism, tech geekery, anti-DRM protest, and other such nonsense, you'd probably enjoy him. His YA novels (Pirate Cinema and Little Brother) are great fun if sometimes a bit dark, and books like Down and Out In the Magic Kingdom, Eastern Standard Tribe, and the like are great and occasionally quite surreal. I really need to his collaboration with Charles Stross
-And speaking of Charles Stross, I'm willing to recommend even works of his I haven't read on confidence. The Laundry Files is rock-solid pulp horror sci-fi that borrows from Lovecraft, cold-war thrillers, James Bond, Modesty Blaise, internet folklore, real-world folklore and conspiracy theories, office bureaucracy, institutional computing and science, and all kinds of other resources. It can be blackly comedic at one turn and utterly chilling the next. It's just really good. And there's nothing else like it. ...Except maybe Delta Green. And from what I've heard, Accelerando, Rule 34, and the rest of his books are just as good.
-Speaking of good, Terry Pratchett wrote Sci-fi. Man, I need to finish the Long Earth books. But even the first one was excellent. Cowritten with Stephen Baxter, it's got traces of Pratchett's sense of humor but still more of his empathy and his distinctly warped mind--his ability to look at a world different from our own and not just take real-world parallels for granted. His worlds are full of things that on the face of it seem insane, but as soon as you think about them, they make perfect sense and of course things developed that way. How could they not? That's the hallmark of excellent world building.
-I just read Planetes, and that's also quite good. Near-future, set in space, chronicling the adventures of a ship tasked with clearing space junk out of orbit. It's... flawed (I've heard the anime might be better), but it's still Makoto Yukimura, and his care and attention to detail and latent talents for storytelling shine through even the roughest patches. Even at its lowest point, Planetes has absolutely beautiful moments that I can't imagine any other mangaka writing the same way. It's beautiful and thoughtful and so very human.
-I'm bending all the rules but what the heck, Planetes is well over a decade old so I might as well bring up Cowboy Bebop. I know, at over 20 it's not quite modern anymore but it's just... so... so good. If you haven't seen it, you should. Go ahead, treat yourself. Run, don't walk, grab a copy of the dub, and prepare to sit down for a lot of hours because I don't binge shows ever but I pretty much binged this. It's that good.
-While you're at it, Firefly is good. Obviously.
-I should stop going back or pretty soon I'll be recommending Snow Crash (go read Snow Crash, it's excellent), so let me talk about a book I've basically never seen anyone talk about that I read years ago. How to Live Safely in a Science Fictional Universe, by Charles Yu, is a truly surreal novel about a time machine mechanic looking for his father... sort of. If you appreciate comprehensible, clear narratives, this may not be your book. But it definitely has a distinct charm to it.