I like Postgres, a nice easy step from "Horr-acle"
Still a long way to go but after 20 years as an Oracle DBA, I'm really digging Postgres, it's very familiar in feel and a lot of PG's features map nicely to those in Oracle. At the very least Postgres beats SQL Server hands down for concurrency, SQL Server is an object locking festival on speed, I've never worked on a DB like SQLSvr for such draconian locking. And lLet's not even get started with "(nolock)" that every dev thinks is so great, yeah until you commit to using the data you got off those dirty-reads and the base trx gets rolled back!!