[ScottBurson]

I wouldn't even consider using MySQL. Postgres (aka PostgreSQL) is an industrial-strength open-source RDBMS.

I can't comment on the non-relational options as I've never used them, but for your data volume I would expect Postgres to be adequate.

[michaelmior]

MySQL is also an industrial-strength open-source RDBMS. Postgres might a better option, but MySQL is worth considering as well.