Hi @HowardTJMoon
My absolute favourite in recent years is the Bobiverse series by Dennis E Taylor. The first book is We are Legion (We are Bob). The first three books were written as one story arc. Books 4 and 5 I think were added on because the first three were so popular, there was a bit of a cliff hanger at the end of book 5 so I'm keeping my fingers crossed that there will be a book 6.
I love John Scalzi generally except for his war books, especially Lock In and its follow up Head On, there is a choice of narrators both are good but I slightly prefer Wil Wheaton. The Dispatcher series is pretty good too and there are a load of stand alone books like Agent to the Stars, Constituent Services and Starter Villain that are very enjoyable.
I like the Children of Time series by Adrian Tchaikovsky, but have tried a few of his other books and not liked them as much except for Service Model which was quirky and quite sweet.
For incredibly long and involved stories the Revelation Space series by Alastair Reynolds is fantastic. I have mostly read these in print form though as I am a very fast reader, I don't know that I could dedicate 27 hours of listening to one book but if you are the type to have a book running for several hours every day then it would work well.
I really enjoyed the Murderbot Diaries by Martha Wells, these come in narrated form or dramatised form. I much, much prefer the narrated ones and found the dramatised ones to be a bit clunkier and slightly harder to follow. Some of the books are quite short so not great value on Audible, which has definitely bothered some reviewers.