A Game of Thrones is a great book and the start of Martin's fantasy deconstruction. It's also pretty mature and graphic in places. I don't know how old you are, but in comparison to the other titles you listed it's much darker in tone and far more violent. It also has fabulous characters which can't be labeled as either "good" or "evil" and provides a great look at emotions and motivation. This series isn't a light read by any means, so just be prepared.
FANTASY
The Dark Glory War by Michael A. Stackpole: Like Martin, Stackpole's book serves as a deconstruction of classic fantasy, but takes more pages from Tolkien with his races and the overarching plot. It's the first of a series, like many on this following list. They're tightly written, wonderfully paced, and wholly overlooked by many fans of the genre. Give the series a try. I'd say more about it, but almost any detail could spoil the ending revelations.
Dragon Weather by Lawrence Watt-Evans: Another first in a trilogy. The main character is well-developed and a pleasure to read. Much of the first book chronicles his journey from a slave to a lord. Admittedly, the third book in the series isn't as good as the first two, but the overall trilogy presents an interesting look at the dragon mythos.
The Death of the Necromancer by Martha Wells: This one can be a bit hard to find but very worth it. Unlike the previous two on this list, it's a standalone and not typical high-fantasy fare. The setting has overtones of Victorian England while being its own separate world. Unique in its atmosphere and characters, none of whom are whitewashed heroes and all of whom have their secrets and skeletons. Wells does a great job in revealing tantalizing hints about the origins of her cast without ever breaking the mystique or losing interest. Wonderful novel, and I wish their were more.
Dragon's Winter by Elizabeth A. Lynn: Lynn has always been a poetic writer, but this is her opus. It reads like a send-up to Tolkien, but unlike most in this genre, Lynn's actually put quite a bit of thought into her world, its legends, and the way the magic works. The characters are beautifully drawn, some of the scenes she writes will bring tears to your eyes, the whole thing is just magic. She wrote a sequel about ten years after this one came out. It's good, but not as good. This book about shapeshifters and brothers is truly a gem.
The Art of Arrow Cutting by Stephen Dedman: This is the first of a short series, and one of the few modern fantasies I actually enjoyed. Perhaps that's because Dedman takes his lore and fantasy from Eastern and Japanese sources rather than standard western fare. Quirky characters and an engaging murder plot drive the story forward. The second book is much darker in tone and far more gruesome.
SF (nitpicking note, don't call it "sci-fi" around hardcore fans or the writers)
Warchild by Karin Lowachee: I can't recommend this book highly enough. I recommend it to fans of the genre and those who normally turn their nose up at SF. It's truly a masterpiece. It tells the story of one boy in the middle of a galactic war. Seems like standard space opera fare until you actually start reading it. Lowachee is a master of emotion and character development. Your heart bleeds for the protagonist. And her villain is the stuff of nightmares. I still get chills reading the climax. The rest of this too-brief series is also brilliant, though the first book holds a special place on my shelf. Be warned, though, very mature themes throughout. Could make some people uncomfortable.
An Exchange of Hostages by Susan Matthews: Another dark, thematic space opera deconstruction here. This one centers around the very uncomfortable topic of torture...and a society that has evolved to demand it. Though written almost 20 years ago (unless I'm mistaken), it's very relevant today. Great read, and another with (surprise, surprise) great characters.
A Scanner Darkly by Philip K. Dick: One of my favorite Dick novels. I always recommend a few, but this one is probably the most accessible. In it, Dick paints a picture of a world very much like the one we live in now. His main character is a narc, taking drugs to maintain his cover, and slowly losing his mind to them. The novel revolves around his spiral downward, but the end is not what you'd expect. Particularly moving because of how much Dick put of himself and his friends into this book. Also be sure to check out Do Androids Dream of Electric Sheep (the basis for the movie Blade Runner), The Man in the High Castle, and UBIK.
Idlewild by Nick Sagan: This one's a throwback to the cyberpunk genre, and another first in a series. The main character is suffering from amnesia while attending school in a virtual reality program. He's also been marked for death, and he doesn't know why or who might be responsible. The plot itself isn't the freshest thing out there, but the writing and characters make it worth the read.
Alright, that's enough wall-of-texting from me. If you need more recommendations, I have plenty.
