I love DVD Decryptor, however, for the sake of convenience, nothing beats AnyDVD. With DVD Decryptor you need to rip the movie to your hard drive as either an image which can then be mounted in a virtual drive(or burned to a DL disc if you want) or as a set of files which can then be processed. This takes time. AnyDVD allows whatever backup program you want to access the DVD on the fly. If I do a movie only backup with AnyDVD I can be done with the original disc in 15 minutes and have the files ready to burn in that time, as well. With DVD Decryptor, it takes 15 minutes to simply rip the files, but, then you still have to process them with your back up program. That's another 10-15 minutes potentially.
Bottom line, if you want something free that works but takes a bit longer, DVD Decryptor rocks. If you want convenience and speed and don't mind paying for it, AnyDVD is definitely an excellent choice. I just bought it recently and am absolutely loving it. Combined with CloneDVD you can't go wrong. Of course, AnyDVD will work with any backup program, but, I just find the CloneDVD/AnyDVD pair to be a great and easy way to back up my dvd's.