DVD Shrink + Nero is the best all around solution.
If you're burning a movie with lots of special effects or a really sharp picture (LOTR and Muholland Drive come to mind) make sure you do a deep analysis and set the Adaptive Error Compensation to "maximum sharpness".
Otherwise just use the default setting.
DVD Decrypter is GREAT if you have a DVD with a scratch(s) in it that doesn't play right anymore. The software somehow compensates for the scratch. I have no idea how it reads what's behind that divot but it does.
Just decrypt the files to your hard drive and then process them with DVD Shrink as you would reading from the DVD drive.
Scratches are pretty much the only time I use DVD Decrypter.
“The democracy will cease to exist when you take away from those who are willing to work and give to those who would not” - Thomas Jefferson, 1801.