Well that's unexpected! I'm aware that Oracle has a few features pg doesn't, and replication is supposed to be easier, but at extraordinary cost and with the added bonus of supporting one of the worst companies in tech.
I don't really think you can even compare them as they serve totally different markets. If I was the CTO at a Fortune 500 and needed a DB for my new global logistics system, fine, Oracle would be in the running. Since this is HN though, I was thinking in terms of startups - and a startup choosing Oracle would be pure insanity unless they had an amazingly good reason.