I am looking for a stable and production ready file manager / file explorer for (Ubuntu) Linux, which has a similar approach on UI and directory browsing as the standard Finder application on Mac OSX computers. Any recommandations anybody?
It's the file explorer bundled in Elementary OS. The graphic interface is clearly inspired by the OSX Finder so I believe it's what you're looking for.
Add the elementary repo
sudo add-apt-repository ppa:elementary-os/stable
sudo apt-get update
sudo apt-get install pantheon-files
sudo apt-get install pantheon-files-plugin-ubuntuone pantheon-files-plugin-dropbox
In my opinion, Pantheon looks very much like a prettier version of Thunar (from XFCE) which you might want to check out as a lightweight alternative.
sudo apt-get install thunar