Microsoft SQL Server

SQL Server is a great system to develop databases with great functionalities like jobs, procedures, functions ans so one

For me the only think not so good is performance for bigger batabases, but for me between 10GiB and 15GiB works fine

MS SQL Server is certainly a competently relational database engine, with reporting service and now R.
Easy to install for small onpremise application.
Easy to administer, easy to backup, easy because it is a Microsoft application.
It is so easy that most of the application today I work on seem to be pulling data from SQL into Excel and or Power BI.
You can start from free version and expand as time goes by.
The management studio take the pain our of scripting, and the online support community most likely have your questions answered with T-SQL scripts for copy and pasting.
If you deciding on an option for an Relational Database system - you should look at this as your most productive option. It allows you to focus on the problem by making the technology easy.

The new the version, the more memory intensive this management studio will become.
Microsoft need to create some more easy to use tool for change control and change tracking.
Backward compatibility - if you used a higher version during development, then it become a pain to use a lower version during production environment.

Is quite secure, it guarantees the security of the databases, it is very easy to configure unlike other database management programs, the installation and configuration is easier. And it also has data recovery support.

Cost, there is a free version that can be used, however for more advanced data-driven applications and functions, you will need to make a considerable investment in higher versions of the software. Also, additional investments in Microsoft software may be necessary if your company uses some or no Microsoft infrastructure.