CCC vs. Super Duper ?

They are both equally reliable in my experience. CCC has the edge in my opinion because it can be configured for schedules and different backup formats much easier than SD. SD has a difficult scripting language that I think makes it less usable for typical needs. If you are in academia CCC is free. If not it's donationware. SD must be purchased for any use other than a full disk clone. CCC is slightly faster than SD, but not by much.

both work great for me and I never had any problems with either of them. I'd say either one is just fine.

I use Carbon Copy Cloner, but I have not heard of any downside for using SuperDuper. SuperDuper is fully functional for its main purpose, making a bootable clone, but there are some features that are crippled until a shareware fee is paid. Carbon Copy Cloner is fully functional for all features, although the developer asks that users consider making a donation (user chooses amount) to support further development. The full feature sets are obviously different.

But for the basic function of making a bootable clone, I think both utilities use the same method. Therefore, I think they produce identical results.

You can also use Apple's Disk Utility to make a bootable duplicate (on the Restore tab). However, you need to be booted from another volume (not the one you want to duplicate); you can use your Mac OS installation disc. With the two cloning utilities, you can duplicate the volume that is currently booted. However, it may still be best to be booted from a different volume, if that is possible.