Postgres
That is all.
Microsoft is bumping up the price of its SQL Server database for the first time in four years. The company said Tuesday that the Standard and Enterprise editions of SQL Server 2008 R2, coming next year, will see increases in the price you pay per processor. SQL Server 2008 R2 Standard Edition will be available at a price per …
..which is probably why it's more expensive.
Oracle's still miles ahead of SQL server, but it is in my experience far more complex. Still, for a lot of users SQL Server does everything they'd ever need to do, and does it with less effort.
For the record I work at the moment almost excusively with SQL server, but I'm man enough to see (and admit) its weaknesses.