which endnote version is better, more stable and has less bugs? end note X9, 20, or 21

As of my last knowledge update in October 2023, EndNote 21 is the latest version available. Generally, newer versions include improvements, bug fixes, and enhancements over previous versions. Therefore, EndNote 21 typically offers better stability and fewer bugs compared to EndNote X9 and EndNote 20. However, the overall experience can vary based on specific system configurations, other software interactions, and individual user needs. It's also worth checking user reviews, forums, and support documentation for insights from other users regarding stability and performance. If you're considering an upgrade, it might be beneficial to evaluate the features specific to your research needs as well.