Both are good programs, I found CloneDVD to be faster than DVD Copy 3, but not by much. I did think that the video quality with DVD Copy 3 was a bit better but I experienced problems with the menus. Weird problems too, like when I was watching the movie and hit the menu button the movie would freeze and the outlining of the menu buttons would show up and I could click on them, it would link to that part of the disc, but it wouldn't show me what I was clicking on and I was still looking at the movie at that spot. Very strange....... Anyway, I've run into a few others who had problems with the menus on movies made with DVD Copy 3, however if you are a main movie only type of person you wouldn't have that problem I'd assume.
Good luck in your decisions, whichever they may be.
P.S. I must say that if you're willing to invest some money and are looking for the best video quality out there, you can't beat Cinema Craft Encoder combined with DVD Rebuilder. Takes a while to do a movie (a couple hours on a high end system) but you'll be amazed with the results.