Here is a writeup from pre-Agile days, about the most effective teams I have been on myself: https://www.linkedin.com/pulse/my-best-dev-team-experience-cliff-berg/

and here is a writeup of a team that became a "rock star" team for its high performance, and to do that, they had a break Scrum (in order to accommodate BDD): https://scaledmarkets.blogspot.com/2017/01/inserting-devops-into-not-very-agile.html