Depends on what you need to do. If you need a simple, but easy to use database, mysql is your best choice. Also you need to consider what kind of support you need. If you are just dinking around, like I do, then mysql will be a great choice. I am currently using postgresql however. It has some advanced features that mysql does not have. But for the most part, it is up to you. Lots of people will be partial to certain RDMS for various reasons.