I use Portainer because it does so good with the UI that we don't have to train our whole team to be Linux bash heros. It provides deep details without leaving details behind you would think could only come from the command line. Portainer is a professional tool that gives us enterprise features we appreciate. ( Will be blogging about this in January. )
I use Portainer because we were all in on Docker Cloud, which gave 2 months notice that they were sunsetting their services. We knew we wanted to migrate to Docker Community Edition, but its lack of UI had us worried until we came across Portainer. Portainer had just release their agent feature, which was a critical feature for us. To date, Portainer has been an outstanding product and we couldn't be happier with it.
We use Portainer because it is only UI tool based tool on the market which is able to manage Linux + Windows containers and multiple Docker Swarms from one place. User auto creation and assignment to teams with LDAP authentication is also one of the key things on environment where is 100+ users.
I use Portainer because it's a great tool to avoid CLI in docker environment, all management in only one screen, awesome. So we can use our time in more important stuff like providing more and better services to our teams and endusers. The Builtin LDAP support and the internal teams helps a lot in diving Dev's in the Devops world. Long live to Portainer. (I work as DevOps in a Big Brazilian Public University )
I use Portainer as a way to disseminate micro-service architectures in my institute and drive innovation forward. Portainer enables an easy to deploy, easy to build platform which decreases the learning curve for deploying containers and micro-services. I am particular interested in offering Portainer as a product in the Research space (i work in one of the bigguest Australian Universities).