Not just a DB project, either. I'd say it's one of the best executed (in a very broad sense of the word) open source projects around, in general.

From end user perspective, they have stable, quality releases with a predictable cycle and subsequent maintenance releases. They have great documentation - one of the best in the industry, much less open source. Things generally work as you'd expect them to, and when not (e.g. for historical or implementation reasons), you have clear and convincing explanations. And so on.

I haven't seen their developer side, but based on other people's feedback, it's also good - high quality bar for code, stringent review process etc. More importantly, they seem to be making the right (= leading to more stable quality releases with great features) technical decisions consistently, which to me is a hallmark of a very well run team.

I also can't remember any publicized "drama" around Postgres, either on the inside (dev disagreements etc), or between the team and the users. It looks like everyone's happy, or at least happy enough.

I don't know what the magic sauce is here, but it feels like many other open source projects could learn a lot from the Postgres team and community.

I second this, the Postgres contributors are consistently setting the bar for the rest of OSS projects out there, it's consistently been my favorite part of the stack for a long time now.

Don't forget about their phenomenal #postgresql channel on Freenode. The folks working on Postgres have been gracious enough to patiently answer my not always fully baked questions for the past 5 years on there, they're a bottomless treasure trove of best practices and pragmatic advice.

I'd say it is the best DB hands down. Open source or otherwise.