I've been using Libby for quite a few years and it's my favorite. I love being able to find nearly any book and have the audible version within 6 weeks. I use it on my long runs and I am always amazed how easily I can tune out the world with a good book playing the background.
Use this free app to open up the amazing world of library e-books. I started doing this a few years ago and it's a big hit in my family. Most public libraries support Libby. Place books on hold, wait a few weeks for the app to notify you, and then read on your phone or kindle. This really feels like the way libraries should work in the modern era.