SQL Server was pretty good until they went the Oracle way with their licensing shenanigans, but even with that they were a lot cheaper than Oracle. In fact SQL server was one of the few great products that came out of MS.
Having written a rust client for it, even their documentation is absolutely stellar. You just read how the protocol works from the PDF and implement it.
Can't say the same about Oracle.
SQL Server started as a source fork of Sybase.