I hope you ment Fab decrypter. they are both great and updated all the time. anydvd is both, a on the fly decrypter and ripper. fab is only a ripper which also break the encryptions. don't need to buy anydvd, fab is good enough.
It all depends on your preference. That is a loaded question in these forums and you will get many differeing opinions. DVDfab HD decrypter is the latest version and the only free version still being updated. Anydvd when used in conjunction with clonedvd is a slam dunk combination. For ease of use I think the anydvd / clonedvd combo can't be beat, this is your one click combo. The drawback to this is they are pay programs, but have a free 21 day trial HERE.
Dvdfab HD decrypter is a free program that removes the encryptions very well and saves the files to your hard drive, then you must use another program to burn those files to disc. While it is not a one click solution it is a free tool that works very well and there are free programs out there that transcode the files to dvd for you.
Esentially dvdfab HD decrypter and anydvd do the same thing. They both rip (while anydvd's ripper is not what it used to be) and they both remove encryption. Anydvd's actual funtion is to make your burning and transcoding programs believe there is no protection on the dvd you are trying to back up. The added bonus is that anydvd will do this all while another program is transcoding and burning a dvd.
You would have to take that on a Dvd by Dvd basis, but it would be easy for you to compare. Make sure you have both programs installed, then take each Dvd you want to backup, try one program first & then the other until either Dvd Decrypter or AnyDvd let you down. You are asking people to compare a program that hasn't been updated in at least 3 years against a program that is still being updated, why? Personally there is no best, better or whatever, as long as the program that you use to rip gets the job done that should be good enough.