Microsoft will only deploy on Microsft.

Some tests a few years ago showed the then current version of SQL Server (6.0 I think) against MySQl 3.xx and Oracle.

In a variety of speed tests, SQL Server was (from memory) about 9 times slower and Oracle over 20 times slower.

With the open development methods and platform independence, MySQl & PostgreSql are streets ahead of anything else for 'normal' commercial use. By which I mean complex databases up to 1 Terrabyte.

Easy to backup too, with simple file snapshots at regular intervals.