mysql really isn't that bad. It has an OSX installer, just double click it. No need to configure anything. I think there is one command you paste into the terminal but you only need to do that once when you install it.
Get an app called cocoamysql to connect to it. it has your query window as well as graphical control over making databases and tables, entering data, etc.
And it's free.
Reports and graphs and pretty user interfaces are not included. You have to make your own with PHP or something. If you are not technical this could be the deal killer for you.
On the other hand there are applications out there that will produce reports from sql databases. You might save a little money by using a free db and just paying for the report generator.
Another DB is SQLite. I've never tried it but there seem to be lots of apps with it built in. So you may not have to install it at all.
FMP is very easy to use but it is not an SQL DB. I think there are ad-ons that will let you connect via ODBC, but last I heard it was pretty limited. FMP's strength is in whipping up nice interfaces fast, if your database is intended to have a person sitting in front of it all day then you can't beat it. If you are going to do complicated queries with multiple tables you'll be better off with a real SQL server.
Definitely checkout 4D, lots of people swear by it.