By now, you probably have heard many great things about Docker's approach to DevOps. I first looked into Docker in 2015, when I was mentoring a GSoC project, and the project had a need to open new Drupal 8 sandbox very often. Since then I have been pushing updates to the official Docker Drupal library.
The latest version Zen 7.x-6.x adopted Style-guide Driven Development approach. For those who are not familiar with the Style-guide Driven Development, you should watch John Albin's presentation. The new aGov distribution theme is also built on top of Zen 7.x-6.x. Style-guide Driven Development is awesome, and the latest Zen 7.x-6.x will be released very soon. However, getting started with subtheming Zen 7.x-6.x can take a lot of learning.