DeployHQ simplifies the deployment of projects on production servers. The usage is really very simple and it eliminates many hassles during version upgrades. The service is very reliable.

Really easy to deploy WordPress sites through an easy to use interface, rather than opaque config files

Having used DeployHQ for many years and see it grow in features it is difficult to pin down a favourite thing, however the simplicity of both the UI and zero-to-first-deploy always comes to mind. It is the go to tool in any company I work at to manage web app deployments