Properly set up, with a proper backup routine and regular check ups i would argue there's not much difference between Joomla and WordPress. Also Drupal having 3 major versions in parallel doesn't help. And the marketplace for 3rd party extensions is the worst.
The most customizable of the bunch is Drupal for sure, but it is also the most work intensive. The market of 3rd party templates and other extensions is much bigger for WP, but honestly I use only a handful of Plugins and if a client needs something tailor-made, then I have to custom code it anyway. I would argue it is as easy to setup and use as WordPress, but when it comes to custom templating i think Joomla is easier and smarter. But I think the overall package is very solid, customizibility is good, good 3rd party software is available. It's a open source project with everything that comes with it, including every mistake going public and heated discussions between contributors. Joomlas development has some issues, that's true. I have worked with Joomla, WP, Drupal (and other CMS) and all these solutions have pros and cons. I have the suspicion most people hating on it haven't spent more than a few days with working with joomla.
I really don't get the hate Joomla is getting in these Comments.
