Instant Copy is a better program than DVD2one. I've used both, and while DVD2one is refreshingly simple, at the end of the day, Instant Copy produces a better image, retains menus, allows greater control, and is really the only option if you want to backup television dvds (not entirely true, but it's tons easier with Instant Copy than with DVD2one).
The only thing that sucks about Instant Copy is that it won't automatically create a 4.3 gig disc image if you set it to 4.3. It usually comes in a few hundred megs less than that. The only thing you have to do is set the final output size to 4.5-4.6gigs, but if you go over the 4.3 gig DVD blank limit, you've got to start all over. At 2 hours per disc, it's a pain. The good thing is that even if the image is only 3.8-4.1 gigs, it still looks great. The bad thing is that it will piss you off knowing that there's still 300-500megs of information that you could have used to make the image quality look better.
There are some tools floating that estimate what to set the final output size to have it come out to 4.35 gigs, but even if you use less than the full disc, I think the image is a little better than DVD2one.
Here are a few pages with examples from Episode 2. There's another program out there called DVD95copy which has been making a few waves, but I've been avoiding it because of some of the reviews. That being said, it appears to be the winner in the link below. (To notice the subtle differences, download the images, rename them to 1.jpg, 2.jpg, etc..., and then flip between them using ACDsee.)
Episode II Original vs. DVD95copy vs. DVD2one vs. Instant Copy
X-men 1.5 Original vs. DVD95copy
Doom9 Poll: Which do you Prefer?
I'd love to see some more quality comparisons. That being said, for a regular 2 hour movie, both DVD2one and Instant Copy are pretty damn good.