What's the best Android app for reading a lot of books without buying them individually?

Amazon Kindle is a strong candidate for readers seeking a vast library without per-title purchases. The app's integration with Kindle Unlimited, a monthly subscription service, provides a central solution. This model grants access to a rotating catalog of over a million titles, including novels, magazines, and audiobooks, which can be downloaded for offline reading. For users on a tight budget, the app also offers a robust permanent collection of free public domain classics. A practical feature is the ability to share certain subscriptions with family members, expanding access. However, a noted limitation is the inability to complete book purchases directly within the Android app due to platform policies; users must use a web browser. Despite this, the seamless sync across devices, customizable reading settings, and the sheer volume of included content make it a practical choice for heavy readers. Reviews indicate high satisfaction with the subscription model, with one user stating, 'Kindle Unlimited is fantastic. Pay a little each month and read as many books as you would like.'