Here is another book series that hasn't been covered here before, but it is really fantastic. It's a two-book story, so it isn't a long, drawn out epic, but it is densely packed with excitement and action.
The Succession series, by Scott Westerfeld
"The undead Emperor has ruled his mighty interstellar empire of eighty human worlds for sixteen hundred years. Because he can grant a form of eternal life, creating an elite known as the Risen, his power has been absolute. He and his sister, the Child Empress, who is eternally a little girl, are worshiped as living gods. No one can touch them.
Not until the Rix, machine-augmented humans who worship very different gods: AI compound minds of planetary extent. The Rix are cool, relentless fanatics, and their only goal is to propagate such AIs throughout the galaxy. They seek to end, by any means necessary, the Emperor's prolonged tyranny of one and supplant it with an eternal cybernetic dynasty of their own. They begin by taking the Child Empress hostage. Captain Laurent Zai of the Imperial Frigate Lynx is tasked with her rescue.
Separated by light-years, bound by an unlikely love, Zai and pacifist senator Nara Oxham must each in their own way, face the challenge of the Rix, and they each will hold the fate of the empire in their hands. The Risen Empire is the first great space opera of the twenty-first century."
The Killing of Worlds, Book Description:
"Captain Laurent Zai of the Imperial frigate Lynx is a walking dead man. Unjustly held responsible for the death of the Child Empress, sister of the immortal Emperor, Zai has been sent to fight an unwinnable battle. The Lynx must stop a vastly superior Rix ship from reaching the planet Legis, a suicide mission that will almost certainly end in oblivion for Captain Zai and his crew.
On the planet Legis below, a Rix compound mind--a massive emergent AI formed from every computer on the planet--as been isolated by their Imperial blockade. But the mind has guided a lone Rix commando, Herd, to the planet's frozen north, and will soon order a desperate attempt to seize a polar communications array and break the blockade. Herd is a single warrior against an Imperial army, but moving silently behind her is the intelligence of an entire planet.
Ten light-years away, Captain Zai's true love, the psychic (some say mad) Senator Nara Oxham is engaged in a deadly game of political intrigue. From her position on the Emperor's War Council, Senator Oxham must find a way to forestall the Emperor's final solution if the blockade is broken: a nuclear strike to destroy the compound mind, which will also kill millions of Imperial citizens. She suspects that the Emperor has a hidden weakness discovered, by the mind, a secret so dangerous to his immortal dynasty that to prevent its discovery the Emperor is willing to countenance the ultimate crime. . . .
The killing of worlds.
With this powerful conclusion to the first story arc of Succession, Scott Westerfeld confirms his stature as one of the leading writers of high space opera."
Scott Westerfeld maybe better-known for his Uglies and Pretties books, but these novels appealed to me because they have a similarity to many sci-fi works that I have read and loved, but they bring something very distinct and unique at the same time.
The politics of the worlds remind me of Dune, the undead rulers remind me of the Chronicles of Riddick, and the whole story has a techno-thriller vibe, coupled with epic space battles. I wish he'd write more books based on this world.
Author's website: http://scottwesterfeld.com/