Well, the ones that make life most worth living are freedom of speech, freedom from search and seizure, etc.
However, the most important ones are the ones that protect the existence of the above rights. So I'd go with the 6th amendment (without an attorney, the fact that you have "rights" written down on paper would not help you assert them if the government charged you with a crime) and the 2nd amendment (if things really get out of hand, an armed populace is the last true defense against government tyranny).