What is the best platform for setting up servers and automating processes?

Nowadays i see a lot of helpers for setting up a server, like Ansible, Docker, Pupet, Chef and so many others.

My interest is in your experience. Are you using something? Best results with one or another, the combination of two together? I read really good things abouot Docker, but i don't know if start learning it maybe result in a mess, or i need to learn something more like ansible or other dependencies.