LibriVox

Pros

• My experience with Librivox has been fantastic and the books I've listened to so far do not sound amateur. The Adventures of Sherlock Holmes read by Ruth Golding is one of the best I've listened to on any platform.
• Check librivox.org for older works out of copyright.
• There is no other legal way to get thousands (possibly millions) of audiobooks for free with zero wait times. Find readers you enjoy and go to town.
• Welcome to the non-audible world! I use Libby and Librivox and supplement with Libro.fm, Chirp, and podcasts.
• start at https://librivox.org/ and read all the great classics. It's free, you download the files so you can keep them forever and don't need the internet.

Cons

• If there is an ebook, see Librivox for making an audiobook.
• Librivox.org has audiobooks of public domain works read by volunteers. Quality varies widely, but there's definitely enjoyable content in there.
• Everyone who volunteers to do a librivox recording. Noble efforts but just terrible.
• And not every company making audiobooks has proofreaders. I think most of the stuff in Librivox doesn't for instance.
• But you could also note that Librivox recordings are usually very amateurish in quality.