It depends. Are you a child or young adult? Do you want a straightforward Catechism that uses layman’s terms and clear language? Are you comfortable with the language of moral theology, and wish the most detailed Catechism aimed at bishops?
- YouCat
- Compendium of the Catechism of the Catholic Church
- Catechism of the Catholic Church
Targeted to different audiences, the first two are based on the third one. The third is a “master plan” a blueprint designed to aid bishops in writing “local” catechisms. Another example of a local catechism is the Ukrainian Greek Catholic Church’s Catechism, currently only available in Ukrainian language.
I suggest that if you are unsure, you go to a library, and have a read through several of these Catechisms until you find one you like. I am comfortable with the third option, although sometimes the language used is more technical than you imagine and it truthfully goes over my head. Some interpretation is necessary for proper understanding. A degree in moral theology wouldn’t hurt. But the first and second should be extremely clear to the laity and just as useful.