Which open-source CMS is the best?

Building a website with an open-source CMS (content management system) is getting every day more and more popular. So I would like to know which open-source CMS your prefer or think that is the best to maintain a website.

For me it are Wordpress and Drupal, let me know your opinion.

phpbb3 , joomla

hey....
i think phpbb and joomla are best.....
both are pretty better than other

For me Joomla, WordPress and drupal works fine!

i think more better for cms are these.
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joomla, wordpress, and drupal are the best for CMS.