Growing up, I read a lot, however most of what I read was history books, but I did engage in the occasioal novel, which were mostly Star Wars ones. But that all changed in 9th Grade when I read House Atreides by Brian Herbert and Kevin J Anderson (who wrote most of the Star Wars books I read). After that I got into the Halo books and from there I kind of started to open up my horizons of sci fi literature but not by much. I've been known to favour reading established and well-known series over individual novels, but I'm working to change that. As for my favourite Sci-Fi novels, that's a tough one, it's easier for me to name my top six sci-fi series but yeah books, hmm.
Dune: this book was the first non-Star Wars or Star Trek sci-fi book I ever read and well, I love the Dune Universe. This was the novel that really got me into fiction, and I was notorious for loving it along with the Halo books in high school.
Starship Troopers: As I entered college I started reading more and more books and one of the first books I bought in college was Starship Troopers. I love this novel, it defined how I approach Sci Fi, and probably was the major driving force (and Halo) that would get me into Mass Effect, Warhammer 40k, and the Honorverse. This is one of the few non-series sci fi books I've read. It is a great novel by Heinlein and it really shows just how pathetic the movie adaptation really is.
Vampire Hunter D: I cannot stop talking about how much I love this book and the whole series. It's more of a novella than a novel, being only 160ish pages long but it is an epic quest of sci-fi fantasy glory. I love how the entire series is post-dystopia, where Vampires are slowly loosing their hold over humanity, but with their knowledge and combination of both magic and physics, the Vampires aren't going down without a fight.
Speaker For the Dead: The second book in the Ender Series and the only other book aside from the first one that I finished, I'll save my more than negative thoughts on Xenocide, this is a good novel. I love how Card sets up the colony, fleshes out the characters and goes about describing their day-to-day interactions and activities.
Nightbringer: So I really, really needed a space opera, and one of my friends recommended G. MacNeil's book Nightbringer. Set in the Dystopian 41st Millenium of 40k, Nightbringer is anything but dystopian. The characters are well written the plot is engaging and it is an epic space adventure. It is one of six books in the series, not counting the Iron Warriors spin off books and the other Ultramarines novels. So if you like Space Knights, space battles and mysterious, ancient artefacts, then Nightbringer a great read.
Challenger's Hope: I haven't read this book in ages or even thought about it, but well, yeah I liked it. Don't know how well it would hold up now, but still I enjoyed it back in 10th Grade. It's the second in a series, where there is some kind of space civil war going on, and the captain of a starship is facing a mutiny so he has to press-gang the civilian colonists he's transporting into the militia to fight off the mutineers. Overall it was enjoyable and a good piece of life on a starship.
These ones were good but just didn't make the cut.
Republic Commando Hard Contact, a Star Wars novel in the gritty and ever great Republic Commando series, it follows Omega Squadron in their attempt to liberate a world from the CIS. My favourite line was the one about the lizard people on the world cook their dead. The reason it didn't make the list is since the series as a whole is amazing, The trials and journeys the clones face happens over all five books, making it a great series rather than individual novel.
Siege of Castellex: Ever wanted to read a novel about the bad guys and watch them succeed? Well that is what Siege of Castellex is about. Following the Iron Warriors Traitor Legion as they fight off an Ork invasion of their world, it follows the Third Grand Company and all the back-stabbing and ambition that Chaos is known for. C. L. Werner's characters are despicable, irredeemable villains that are written in a way that you just want to keep on reading. I thoroughly enjoyed this novel and all the vileness it brought with it.
Anyway that's my list of the top six and two bonus sci fi novels that I truly love. Hopefully there will be more to add this time next year, since I've got On Basilisk Station, Foundation, Hyperion, and the rest of the Ultramarines Series to read.