The answer to this question depends on a variety of factors and is ultimately up to personal preference. Both Pfizer and Moderna are effective vaccines in terms of preventing the spread of the virus, however, the differences between the two lie in the delivery and storage methods. Pfizer requires two doses and needs to be stored at extremely cold temperatures, while Moderna only requires one dose and can be stored at regular refrigerator temperatures. In terms of side effects, both vaccines have been found to have similar levels of efficacy and mild side effects, such as fatigue, headaches, and body aches. Ultimately, both vaccines are effective and safe, so it is up to the individual to decide which one is best for them.