Expeditionary Force is a fun sci-fi saga with great narration and lots of funny bits. If you're not paying attention and miss half a chapter it doesn't really matter too much. Book 7.5 is a full cast epic production with a few well known sci-fi actors.

If you're looking for something that'd you'd get at the pharmacy for $10 then Jack Reacher is pretty fun for the first 10 or so books. I find the most interesting bit being that they're contemporary and basically released annually with the first being released in 1997. You can see the technology change and the world around Jack change. I tapped out after book 20 or so but it was an enjoyable enough experience.

Any of the books narrated by Peter Kenny in the Culture series by Iain M. Banks. Banks’ books are my favorite Sci-Fi, and Kenny does such an impressive job of doing an understated reading. He “does the voices” really well so you can tell the characters apart, but it’s all very subtle and easy to listen to. He also does the “techno-babble” so damn well, and captures Banks’ sense of humor perfectly.

I think there’s only one of the Culture books that he didn’t narrate, can’t remember which at the moment.

• Red Rising
• Golden Son
• Morning Star

All narrated by Tim Gerard Reynolds, and he's AWESOME.

THEN also

• Iron Gold
• Dark Age
• Light Bringer

Also narrated by Tim Gerard Reynolds, but there are also more voiced character in these, so there's more variety, and it's great.

I really like Red Rising.