We have a number of MySql installations, which have multiplied quite a bit over the last few years. I started using it in another shop about 10 years ago, and although its feature set always seems to lag SQL Server's by a year or two, I like its ease of use, community support, and unambiguous licencing (it's a free Open Source product).

I'm increasingly uncertain about Microsoft's future, and having an Open Source alternative RDBMS seems to make sense to me. Not all the eggs need to go in one basket.