Which files and folders are preferred for saving, with a brief description of what they store?

By default, the following folders and directories are marked in the firmware for saving:

config.plugins.configurationbackup.backupdirs=['/etc/hostname/', '/etc/enigma2/', '/etc/keys/', '/etc/network/interfaces', '/etc/tuxbox/scce/', '/etc/tuxtxt', '/etc/resolv.conf', '/etc/wpa_supplicant.conf']

They are enough to save all your user settings and data. Mark additional files to save only if you really know what and why you want to save!