MySQL

Vantagens

Known and used by most people as most secure and reliable relational database management system. Accompanies 99.99% uptime. Nothing to fears as open source. Can have millions of helps through community. Offers a wide scope of high accessibility like cluster servers master slave replication. Provides high performance even for large volume projects. Growing and improving frequently. Best for cloud applications and big data applications. Supports by huge no of frameworks.

Desvantagens

Red Hat Enterprise Linux, openSUSE, Fedora, Slackware Linux etc moved to MariaDB.

Vantagens

I like that it has a community edition which allows to get the software for free with community support. In the case of red hat/CEntOS host, a repository settings can be added and the installation is pretty straightforward.
As long as it is correctly setup according to the server resources and expected demand, it runs pretty fast, it is stable and supports lots of connections.

Desvantagens

I feel that it has been starting to loose its backwards compatibility. If you need to use a previous feature, for example, if you want to use the mysql native password, now you need to specify it when creating a user, otherwise, it won't work straightforward with most CMS software. Also, as some datatypes are being improved (which should be a nice to have feature), when migrating to a newer version, restoring a dump can turn into a headache. The users model have also changed, so, if you had a very large users set, you have to do some work to make it work again in newer versions.

Vantagens

I like most the speed of MySQL and capability to support multiple kind of operating systems on various machines

Desvantagens

I don't find anything to dislike in MySQL till yet in my throughout experience.

Vantagens

It's the default standard for many companies. MySQL has grown into a very stable product that never crashes. We've made the move to MariaDB, but found that the tables sometimes get corrupted when restarting a database server under heavy load. With the recent speed improvements to MySQL, we have decided to actually migrate back to MySQL.

Desvantagens

I'd really like if they would spend a bit more time on their CLI interface. As in, syntax highlighting in the CLI, an easier way to scroll through multiline queries when going through the history. I would also like it if we can specify a color scheme to use for the output.

Vantagens

MySQL is a well balanced product, while it is free to use, it also has many features you can find in corporative solutions, like SQL Server and Oracle. If you ever need help, you will find answers almost everywhere, from their own documentation to stackoverflow and other forums, easily. You will have a very short learning curve with MySQL.

Desvantagens

When you need to deal with great amount of data, like some kind of data warehouse structure or huge amount of measures to analyze, you better go other choices. It starts getting too slow with the same hardware other products will work smoothly. But I guess that is not the purpose for MySQL. In the other hand, if you want it to build a transactional system like an e-commerce platform or even a Blog page, it is a very good choice!