Kindle cases protect the scratch-prone Kindle screens, save the device from accidents, etc. The best Kindle cases protect without curtailing the device's usability and easy portability. They are built to last without being expensive. Moreover, sleeveless cases should have magnetic sleep/wake functionality. They also have solid cover magnets that don't let the cover open on their own.

The best Kindle Paperwhite case: OMOTON (provide a tight fit, screen flap stays tight,  textured plastic shell for tight grip, protective plastic screen flap with a faux microsuede interior.)
The second best case (expensive, good looking): Fintie Folio  (almost the same as OMOTON, almost)
The third best Kindle case: Paperwhite Leather Cover (goof quality leather, good plastic backing)
Other good Kindle cases: MoKo Cover Case, Poetic Slimline Portfolio, RooCASE’S Ultra-Slim Vegan Leather Folio Case