Libby/Overdrive? It’s great, except for the 12 weeks I’m waiting for most of the books I want, then they become available during time that I don’t have to read.
I use the Chrome Instant Multi Search extension to search all the libraries+services – about 12 different sites at this point. Between them they have almost every book I want in e-book or audiobook, and by placing holds I can keep a steady queue of books going. Managed 125 books this year that way, the majority of them digital, and free.