Here are a lot of recommendations from me. I tried to order them to a semblance of categories.

Military science fiction

• The Lost Fleet series by Jack Campbell. This is a barebones tactical fleet combat series written by a former US Navy officer. Don’t expect much of character development, but stay for the combat scenarios under imperfect information conditions. Very consistent narration throughout the series and its spin-offs.
• Frontlines series by Marko Kloos. Boots on the ground combat series. The author is good at turning around some common tropes, so the twists tend to be fresh and quite unexpected. As it is narrated in first person, the narration is adequate, though not stellar.

Space operas

• In Fury Born by David Weber. A very long one-shot book, which is superbly narrated. It teared me up a few times.
• The Icarus Hunt by Timothy Zahn. The author is best known for his Thrawn Trilogy, and this book also feels like set in a Star Wars universe, even though a little more light-hearted. Very good reveal at the end, and the narration is more like acting.
• Troy Rising series by John Ringo. One of the few modern uplifting science fiction works I can think of. Another good narration.
• The Interdependence series by John Scalzi. Unless you can’t stand Will Wheaton’s voice, this is a good series. Scalzi matured as an author and Wheaton as a narrator, and together they deliver a solid trilogy. Everything else by Scalzi is hit-and-miss, either due to very raw writing, money-grabbing pointless sequels that are essentially a retelling of an earlier book, or Wheaton’s tendency to turn even the most tragic scenes into a joke.

Light-hearted books

• Project Hail Mary by Andy Weir. The book is essentially a high school general science book dressed as science fiction, but the writing style and narration gave me quite a few chuckles.
• Will Save the Galaxy for Food by Yahtzee Croshaw. One of the few authors who can pull off narrating their own books. It’s got its own sense of dry British humor that I appreciated.

Best author-narrator combos

• Alastair Reynolds, narrated by John Lee. Reynolds’ prose is usually dark (think of Giger-esque organic gothic visuals), and the characters all sound very dramatic. Lee is absolutely perfect for those.
• Neil Gaiman, narrated by Neil Gaiman. He is incredibly inventive, from The Graveyard Book and Neverwhere, to American Gods and Anansi Boys. He is also absolutely perfect in narrating his works. I don’t know whether his collections of short stories got narrated (I only read those), but if they did, they are the closest thing to Ray Bradbury’s short stories you get these days.