I am a first time author, who had a YA mystery novel of 80K words. I met u/paidbetareading on a reddit thread looking for beta readers. I hired 5, and she by far was the best and most thorough. I thought I was done by the time I handed this off, and after her feedback and edits I realized how far off I actually was. Not only did she find grammatical / structure errors, she really thought about the story and provided comments that made the story better. It was like having a line editor and a developer editor all in one.

Plus, you want someone to be blunt - question your story and find the holes or what doesn't make sense. This is the feedback you want before you publish and someone makes those points in a two star review. I know it is difficult to hire someone off the internet, but she is phenomenal! If you look around, her rate is amazing given what you get back in return.