should I update my standard macbook pro early 2011 (4gb ram, 500gb HD, intel core i5) to sierra or high sierra? or should i stay on el capitan? and why?
Only reason to upgrade is if you need Sierra or High Sierra in order to run some software, or you want some of the new features, or you just like to have the latest greatest. Other than that I don't think you will notice any performance improvement.