Dolphin | Homepage
Dolphin is the default file manager in KDE and it features an easy to use interface, tabs, previews, three view modes (icons, details, columns), vertical window splitting, file and folder sorting, service menus, tags, two-mode location bar.
sudo apt-get install dolphin
Nautilus | Homepage
The default file manager in GNOME, Nautilus has an intuitive interface and offers features like previews, sorting, three view modes (icons, list, compact), bookmarks. Nautilus can be expanded via plugins and it also supports context menus.