This poll really needs some qualification. Really, what are we choosing a database Management System for? If we are talking about some very high transaction rate, very large database, then it is difficult to go past Oracle, or even DB/2 (running on a monster mainframe with terebytes of disk storage).
in reply to Database of choice
Is the database the back end storage for a particular application - such as SAP? Then in most cases (SAP is almost DBMS-agnostic) the software supplier has a preferenace for one, or maybe two DBMS's.
Or are we wanting a smaller, several user data base? Then probably MySQL.
At least no one mentioned Access. Or bDase II. Or Reflection.