Being very honest I can state that the most impressive thing about HiveMQ is its fantastic scalability and reliability. We have been able to easily deal with millions of opening connections and messages and this is important to our distributed IoT devices. High availability and enterprise security are also of the highest quality, which makes us feel safe and certain that our data is safe and can be accessed at any time. To give one example, when implementing firmware upgrades to the thousands of devices at once,

What I like best about HiveMQ is its incredible reliability and ability to scale effortlessly. The clustering capabilities are top-notch, allowing you to handle millions of concurrent connections and a massive volume of messages without breaking a sweat, which is essential for large IoT deployments. Plus, the built-in features like message persistence and high availability mean you don't lose data, even during network hiccups or server restarts. It truly feels like an industrial grade messaging backbone that you can trust to just work, day in and day out.

Good documentation that help to setup IoT devices easily with current network system. Minimize setup time, has great support from the community.