SuperDuper! is a good program for cloning your hard drive and doing basic updates to the clone. Carbon Copy Cloner is an excellent cloning tool like SuperDuper! with some basic backup flexibility. However, if you need heavy duty backup capabilities with extensive scheduling and other options, ease of configuration, no-scripting configuration, use of network drives, etc. then Synchronize! Pro X is the best of the three by a long shot. Only Retrospect provides more features such as searchable index files, tape drive support, can backup over multiple media for both tape and CD/DVD backups.
Synchronize! Pro X can even be configured to start a backup automatically whenever the backup drive is connected or brought online.