The open source Files app is solid Windows File Explorer replacement with this new version introducing a complete UI refresh, Office docs preview, support for more file formats and more.
Directory Opus works just like Explorer, but faster. Features include a tabbed interface, duplicate file finder, image converter, and more. Test a fully functional version of Directory Opus for free.
Total Commander is regarded by many as the best replacement for Windows Explorer. Its latest release, version 9.10, looks to further solidify that status with various improvements, support for the W10's Fall Creators Update and support for multiple screens with different DPIs per screen.
For over a decade Total Commander has been the Windows File Manager replacement of choice for system admins and old school power users alike. A major new release (v9.0) offers a wide range of user interface improvements, functional enhancements, and a wave of bug fixes. There's an Android version, too. Download it here.