Both have their place as both are not the same type of program. If you want to backup absolutely everything on the DVD with best quality then DVDxCopy can split the DVD over 2 DVDR's. If you only want 1 DVDR regardless of origianl length and want the movie only then DVD2ONE is your choice.
If the DVD is a single layer DVD5, then neither is the best, DVD Decrypter is your best program for these (and its free).