[sjroot]

I think it depends on your product and where it is at in its lifecycle. If you are building a new product or service, just use an option that is sufficiently stable (Postgres, MySQL, etc). If you are thinking of migrating from one technology to another, you need to figure out which metrics you are trying to improve and see which alternative(s) would provide the performance improvement you are looking for.

That said, when I am making the decision myself, I just go with Postgres.