DVD Decrypter was the best, and it's freeware. It's been a couple years since I checked out the ripping forums, so I don't know if anything's replaced that as the #1 ripping software. The program hasn't been supported since 2005. Here's the wiki page:
http://en.wikipedia.org/wiki/DVD_Decrypter
Here's a basic tutorial:
http://www.mrbass.org/dvdrip/
You should check out VideoHelp for the latest news, tools, tutorials and forums:
http://www.videohelp.com/