I've been using HandBrake for years, but recently when I tried to use it to rip Avatar, it kept saying that I needed to install VLC -- which I had installed already.
So out of frustration, I tried WonderShare's DVD Ripper. It had a much better user interface than HandBrake and it included an iPad preset. It was fast, to, utilizing 10 of my Mac Pro's 16 virtual cores. I now have Avatar on my iPad.
They have a free trial but I paid the $45 for a license.