It may be undeserved now, but MySQL had/has a reputation for a lot of sloppy work for good enough features or for performance. Mysql dropped MyISAM for InnoDB in an effort to undo some of that damage so it's hard for me to say they're not committed to quality now.
But reputations take time to rebuild.
Over the past decade we've seen a lot of different data storage options presented that have exchanged critical data integrity features for speed, architecture, "document storage", or some other fad factor of the day.
I've been using Postgresql in a production environment since 2004, having converted from MySQL and never looked back. I'm not bagging on the other technologies, they're great for certain tasks, its just that Postgresql is great data storage and query engine and I think you'll grow to love it. I recommend the #postgresql community on Freenode as they are helpful and generous with their time.
Someone on HN once said "Postgres is the answer until proven otherwise" and that's a pretty good sentiment.
It’s not the only reason but yes, Postgres has recently made significant advances in parallelism and indexing.