At the end of the day, out of thousands of database administration tools available out there, you can never declare a single one of them to be the best. It all depends on the requirements and the budget of the company/enterprise.
If you have multiple databases and you aren't only on MySQL but other platforms as well, then Navicat is your go-to platform. The simple reason is the ease of setup and cross-database support. It's the most expensive among the three but does bring a lot of features to the table that the other two don't. Datadog is another best option for small-to-medium companies. You can customize the tool according to your preference and get the best out of it. MONyog is the only agentless database monitoring tool and the fact that you'll be able to monitor your database without installing any kind of PHP or .NET agent is exciting.
All three...