Remember there is also MariaDB, quote from they webpage:
MariaDB is a database server that offers drop-in replacement functionality for MySQL. MariaDB is built by some of the original authors of MySQL, with assistance from the broader community of Free and open source software developers. In addition to the core functionality of MySQL, MariaDB offers a rich set of feature enhancements including alternate storage engines, server optimizations, and patches.
I have a lot of respect for MariaDB, but they are aiming to be a drop-in replacement for MySQL. Drizzle is not a drop-in replacement and intentionally broke some compatibility to reach it's goals.
Not denying it, both projects have slightly different goals. But since some people reading this discussion might consider switching from MySQL to Drizzle it doesn't hurt to present them other options, which in some cases might suit them better (depending on what are your exact needs).
MariaDB is a database server that offers drop-in replacement functionality for MySQL. MariaDB is built by some of the original authors of MySQL, with assistance from the broader community of Free and open source software developers. In addition to the core functionality of MySQL, MariaDB offers a rich set of feature enhancements including alternate storage engines, server optimizations, and patches.
http://mariadb.org/