What's the best Content Management System (CMS)?

phpWebSite? (php)
Mambo? (php)
PHPNuke? (php)
OpenPHPNuke? (php)
PostNuke? (php)
WordPress? (php)
WSNLinks? (php)
WSNGallery? (php)
BackEnd CMS? (php)
Tiki? (php)
LogiCreate? (php)
Xoops? (php?)
Plone? (Python)
Zope (Python)
Xist? (Python)
OpenCMS? (Java)
Magnolia? (Java)
Cocoon Apache (Java)
Vanilla? (Rebol)

(Sorry if I left any out)

What is your favorite (does not necessarily have to be in the list, does not have to be free or open source)?

Or if you don't line Content Management Systems, Why Not?

Joomla! (former Mambo)

I use a cms at work, Rythmyx by Percussion. It's the worst thing I have ever had the misfortune to use.

For my own projects I don't use a cms, although I do have some scripts handling my blog. I prefer to write my own code in general.

Joomla and Drupal seem to have good reputations

I use wordpress that I custom ported to work as a non-blog and more of a CMS.

I suspect WordPress may be one of the best free CMSs out there.
With the right tweaking, you can write a static site on it and easily integrate a blog in it, too.

Depends on what you want your CMS to do, though.

Drupal gets my vote (or in my case, vbDrupal, which integrates with vBulletin). I've worked a lot with Joomla as well and like it for certain purposes, but at this point wouldn't use it for my own sites (I use it as appropriate for clients)... the upcoming version 1.5 looks promising. I've also seen some great things done with WordPress, though don't have personal experience with it.