Oracle database is the best
Flashback query, external tables, standby with real time apply, and pl/sql are features that MS SQL Server just cannot match.
IBM DB2 and EnterpriseDB were both motivated to emulate pl/sql (into Postgres, even!) - why Microsoft didn't come to this party is beyond me. Transact SQL was already Sybase's unloved import - the lack of pl/sql is what? NIH hubris?