Saladin is a quite simple, but well-made light-weight dual-pane file manager.
Ranked in these QuestionsQuestion Ranking
Pro Bookmark support
Pro Built-in file viewer
Which even supports a lot of encodings.
Pro Open source
Pro Intuitive usable
All commands use the well-known shortcuts.
Pro Lynx-like motion
Cursor left: parent directory, cursor right: go into directory/zip.
Pro White and dark theme
Con Blocking file operations
E.g. while moving a large directory structure, you can't do anything else.