Have you gone over to opensourcecms.com and tried a few out? They have demos of a bunch of open source cms packages already installed and waiting for you to test drive.
cmsmadesimple a lot. Very easy to install, use, and seo compliant
I do not have any knowledge about CMS.If you give some more details than it will be very helpful to understand.I know about HTML but do not know about CMS.I hope you will give some more details to us here.
Well i'm using Drupal CMS management template it is very robust and content management can be done with few clciks ,i have never seen such user friendly but robust CMS than Drupal.Another popular one is Joomla but it is little complex.