I've had to work with mysql far more than I would ever choose to, because I've mostly worked for small companies, and that's what they usually have. At my last job they didn't have a database yet and the boss had no real preferences other than low cost/free, so we were able to get Postgres instead. At my current job they use mysql, but we're developing an application that needs foreign keys and atomic transactions, so I'll probably get something else to play with soon.

Despite the fact that I like Postgres, some of my most frusterating experiences have involved Postgres and large objects.