Wordpress is most powerful and most customizable. It has a bunch of useful plug-ins developed by users everywhere.
Wordpress is a blogging cms and for seo purpose it has alot of plugins and mods as compare to portal cms (joomla, drupal)
Many good ones, we use joomla, cushy cms and dle, it depends on what your budget is and what you need it to do, most cms are seo friendly.
@mg1313 - very nice looking site, but it has a problem. I clicked "convertibles" and got this "The Ford Motor Company Auto Show website has encountered a technical difficulty. We are working to resolve the problem.". Other links worked. Loved the glass top 'stang.
Ok so edit dosen't work. I haven't done much with Drupal but Wordpress with some plug ins is actually quite good and easy enough. Just pick one and go for it.
Wordpress is a blog tool/program not a content management system. You might want to try Drupal, Geeklog, Joomla, Mambo Open Source, PHP-Nuke , phpWCMS, phpWebSite, Post-Nuke, Siteframe, TYPO3, or Xoops