The other big one is libro.fm, which I also think has the nicest website, for whatever that's worth. There's also Google Play, but they always seem to be more expensive.
I've been using a combination of these three sites (libro.fm, downpour.com, audiobooksnow.com) for many years now. Although I do occasionally need to hop back over to Audible for one of their exclusives, but not often.
Quick note about audiobooksnow.com, they do have a small number of DRM'd titles. Check for a "Downloadable" icon before buying!
I've been using a combination of these three sites (libro.fm, downpour.com, audiobooksnow.com) for many years now. Although I do occasionally need to hop back over to Audible for one of their exclusives, but not often.
Quick note about audiobooksnow.com, they do have a small number of DRM'd titles. Check for a "Downloadable" icon before buying!