At the moment, Alcohol 120% is better than Clone CD. It can copy more protections that Clone CD at the moment, and the authors are always the first to bring new features into the market. Also, Alcohol (full version) lets the user add upto 31 virtual drives compared to Clone CD's one. Alcohol can read and write a multitude of image files, whereas Clone CD can only handle one.
You can download a trial version of Alcohol 120% from
www.alcohol-software.com