Reviews of the audiobooks, either on Amazon or Goodreads.

Patience and practice -- a lot of the free ones are done by computer voice -- so it can be somewhat confusing with words that don't exist (scifi and fantasy, text books). If the company offers free listening for a paragraph or two, that will help. Make a list of books, authors, and readers. That will help find the readers that do well.

Perhaps I'm being a bit dim here, but are you asking people for a way to discover your individual preffered audio voice to listen to? How the hell (excuse the pun) would any random stranger know what type of voice you like to listen to? I must be missing your point here; but if not; I'd suggest you listen to each of the voice options and decide yourself on what you feel is the most pleasant to your ear.

I agree that Audible.com is a good place to go. It has plenty of choices but I'm not sure as to how many readers are available for one book. I've found all the ones I've purchased to be good even when the author of the book is the reader.

I prefer female voices personally. I use audible.com and I can preview the voice before I select a book.

Read some reviews. Amazon has reviews

Personally, if available, I will always choose the ones narrated by the author of the book. I feel that the mannerisms and tone they use are most authentic. It's just read the way it's meant to be read.

That being said, if that's not an option, which is often the case, I listen to the sample and decide based on that.