> In addition, because MySQL is, in my experience, more widely deployed, it’s easier to find and hire engineers with experience deploying and operating it. Postgres is a fine choice, especially if you already have expertise using it on your team, but I’ve personally been burned too many times.

This is opposite my experience. While I do suspect MySQL is more widely deployed, I've seen MySQL more frequently among less-mature teams, and Postgres more frequently among very-mature teams. I've also seen MySQL burn folks more than Postgres.

I do think, however, that both have enjoyed periods of popularity and stability. Right now, I think they're both quite stable, so it's really a coin toss. I find MySQL's behavior to be pretty weird compared to Postgres, and Postgres knowledge tends to translate pretty well to other databases, which are frequently derived from Postgres (Vertica, Redshift, Snowflake, Cockroach, etc.)