Ansible - A free, Python-based platform for configuration management and software deployment, the Ansible platform has a reputation for simplicity and minimalism so admins can get it running quickly—though that's said to come at the expense of some of the product’s overall capabilities.
CFEngine - Perhaps the original configuration management tool (dating back to 1993), CFEngine maintains a vast user base of very large enterprise customers.
Chef - Another major config manager, Chef is generally seen as more Dev focused in comparison to Puppet. Chef gets its name from the concept of writing its configuration schema as “recipes” in Ruby. (That makes you the chef.) It supports all major cloud services, making it popular with cloud-centric infrastructures, though some complain about the steep learning curve.
Puppet - This long-running, widely supported cross-platform configuration management tool has been successfully deployed across a vast array of enterprises. Generally considered more focused on the Ops side of DevOps, it is known to be stable, with a large support community.
SaltStack - Also known simply as Salt, this platform has a focus on modularity that the administrator can leverage based on specific needs. As with Chef, some say mastering the system can initially be difficult.