A lot of people like DVDXCOPY because of it's simplicity. It will copy the 'whole' DVD including extras, menus, special features, ect. - you will usually need 2 discs though from my experience. The program is also setup so you cannot make copies of copies, it also puts a disclaimer before every movie - piracy, blah blah stuff.
With DVD2ONE you just need another program (like DVD Decrypter) to decrypt or 'rip' the original files off the DVD you want to copy. DVD2ONE will then convert those files so that you can use a program like NERO to burn a working copy (movie only).
-VTrider