Biggest difference for me is that MySQL always pushed a simpler user structure while most *nix Postgres packages prefer having corresponding native OS users by default (PAM vs password auth). Also, it always seemed easier to migrate/upgrade MySQL data folders compared to Postgres ones. The specifics aren’t coming to mind right now, though. Finally I know way too many folks who prefer phpMyAdmin, especially when provided from their cheap shared hosting provider.

Don’t get me wrong, I prefer Postgres generally too, but I can definitely see wins to MySQL on ease-of-use. Especially the less standard but more forgiving SQL syntax and simple DESCRIBE commands. Yes the quirks add up for MySQL but Postgres has its share of quirks too.