File managers for Windows

Directory Opus by GPSoftware is an extremely good file manager for Windows and one of my favorite applications. It's fast, has a clean, logical and customizable UI and allows scripting. One nice feature is "Find Duplicate Files" which comes in handy when you need to do some cleanup. It also supports connecting to SFTP servers. It can be configured to replace File Explorer so that when you press Win+E it will open Directory Opus instead.

Another great file manager is XYplorer which is in some ways similar to Directory Opus.