Choosing the right viral vector for your experiment depends on several key factors: integration, cargo capacity, immunogenicity, and duration of expression. AAV is non-integrating and provides long-term expression in non-dividing cells, making it ideal for in vivo work. Lentivirus integrates into the host genome, enabling stable expression in dividing cells, but carries a higher risk of insertional mutagenesis. Adenovirus has a large capacity and high transduction efficiency but triggers strong immune responses. This article provides a framework to help you decide based on your specific experimental needs, including examples of typical applications and trade-offs.